I would have to say that your 2101 is a nice piece for versatility however if you want the full benefit of it you need to do the ppc-210 upgrade that gives you dual s-disc processing for longer algorithms and seamless patch changes. With the implementation fo the ppc-210 you will also need to be on version 3.00 a software. There are many places to get patches for just about any tone you want to achieve. I own one but I don't use it in favor of more of an organic straight up amp tone.
As far as the thought of a preamp like the JMP-1 goes, I too owned one of those. I liked it for a while but always felt that it was too synthetic sounding. This is something that the 2101 also has but I kind of let that go for the use of the effects and other uses. The JMP-1 just doesn't really cop the feel of a true amp. I had used it with the 9005, 9100, and also just as a preamp into a head as slave. I would just assume buy the Marshall head that you like the tones of.
With that in mind, the 900s were not that great. Though the 800s were better and more raw sounding. I found that when it came down to it I prefer the sounds of a JMP 50 watt master akin to the 2204. The single channel amps are better for tone and have none of the channel switching issues. The 2203 or JMP 100 watt master is a classic amp that is if nothing else a formidable asset to your arsenal. This being said I do feel that the later 87 and up 2205/2210 2 channel amps sound incredible. My 1988 2210 is probably the loudest most raw Marshall I have ever played not to mention has the best distortion for thrash and speed metal. My 1977 JMP 50 watt master kills it for tone though.
In the 80s the JCM800 series went through some changes. The 2203 received circuit changes that reduced the # of caps and undeniably changed its tone. The single channel amps 2203/2204 received a facelift that included horizontal inputs that strayed from the vertical inputs of the past. This change came with the inception of the pcb mounted pots. It became a techs' nightmare. Though the 2203 received a circuit change that changed the # of caps the 2204 remained the same thus any year of the 2204 is actually a good amp though you may still want to keep with the nonpcb mounted pots for reliability issues. The 2205/2210 in the early years had great cleans for marshall and so-so distortion. There was a channel bleed issue that was addressed in late 86 that was corrected however the cleans that the amp was known for were somewhat lost in favor of the untamed distortion that arose. The DI in the 800 series was kind of useless but in the late 80s Marshall did begin to use a tube effects loop. The effects loop was nice to have though doesn't compare to today's loops.
Many folks either love or hate their JCM2000 series amps. I personally do not care for them though they do have a few nice features to them. I just think it is Marshall straying from a nononsense amp in favor for versatility. They really lost some of the tone that made a Marshall great. I guess in a way it was an attempt to get a little bit of all the Marshall sounds though not acceling at any. The adjustable pots were a good idea though to make tube changes easier.
Another amp that has that love/hate relationship is the 900 series. The MkIII amps are simliar to the single channel 2203/2204 just with more gain. The dual reverb heads are similar to the 2205/2210 just without the tone and a bit more fizziness to the distortion in an attempt to rival amps like Mesa. If I were to acquire a 900 it would probably be of the MkIII amp variety.
Diode clipping amongst Marshall fans is a hit and miss kind of deal. There are those that do not like it and choose for more of an all tube path, there are those that hate the sag of a rectifier, and there are those that don't care either way. I think when it all boils down to it the matter is personal taste like anything else. I look at it like this: if it sounds good who cares. I am sure that many can make a tube rectified marshall sound like ass just as they can their diode clipping models. There are surely those that can make either sound great also. To me, it is more of a shut up and play philosophy. You can sit back and debate all day but what good is it if you can't make your gear sound good and have your gear make you sound good.
I have yet to try the Stiletto but I am more of the mindset that if you want Marshall you get Marshall. If you want Mesa you get Mesa. This also applies to Fender and every other manufacturer out there.
With regards to your choices of music that you want to emulate, I would suggest getting a combination of three amps. They would be an older all tube Fender like a Twin, either a JCM800 2203/2204 or its JMP predecessor, and maybe a Mesa Mark series amp. These amps will deliver the sounds that you are looking for but you will have to switch among them in order to really nail the tones you are trying to achieve. They do sell little amp switching units in even a stompbox variation so you don't have to invest in Bradshaw or the Mesa equivalent.
In the end, it is going to come down to your own personal taste and what sounds good to your ears. Go out and try different stuff from time to time. You will be surprized what sounds good and there too you may find that you have been chasing a dog in err. I once believed that you needed all kinds of rack stuff to sound good. I also believed that you needed a Floyd Rose tremolo or a really flat neck to shred. These are misconceptions that as you play more you will find are not necessarily so. I have found that tremolo systems can really take away from your tone and a fatter neck will inherently get better tone because there is more to resonate. The rack stuff can be fun but I wouldn't make it the heart and soul of my rig ever again. It is really hard to rid yourself of the synthetic soulless tone that most racks have. Even the Triaxis, to me, sounds like a pale imitation of what it is trying to achieve. Regardless of the path you choose, just remember that it will be your wallet that is affected by your GAS. Some choices will be better than others but until you figure out what it is that you are really looking for be aware that it is an expensive journey.
