Update: finally I had a chance to spend some quality time with Mark V this weekend, tried both suggested approaches and compared it side-by-side with my Mark IV(b).
My set-up: Strat/CU24 connected to A/B pedal; both A/B outs connected to the input jacks on Mark IV/V. Then Mark IV recording out was connected to the mixer; Mark V had it's own 8 Ohm speaker connected to the 4 Ohm speaker jack, the second 4 Ohm jack was connected to 4 Ohm Hot Plate which was then connected to the mixer via Line Out with main dial on HotPlate switched to the Load mode.
Initially, I wanted to try 8 Ohm HotPlate with Mark V but couldn't find it in stock at couple of dealers I tried. One dealer even told me that they backordered and current wait on those is about 8 weeks?? So, I picked up a used 4 Ohm HotPlate at local GC instead to try it out.
I tried to dial my favorite Mark IV lead channel sound on Mark V. It took some (or rather a lot) of tweaking but at the end I got it sound pretty close via built-in speakers. Then I used my headphones connected to the mixer to compare the sounds.
Below are my observations:
The good stuff:
1. It's much easier to dial a good sound with Mark V
2. I liked reverb on Mark V a lot more
Not so good stuff:
1. Even with some mixer tweaking, I wasn't able to adjust the output sound of Mark V/HotPlate to sound nearly as good as Mark IV with Recording out while listening through headphones. The sound became pretty sterile, lost some of it's warmth, sparkling highs and dynamics.
2. I also tried using the Mute (Tuner) output and results weren't very good - a lot of white noise (I don't use noise gate as I had no need for it with Mark IV) and I also realized that since the signal comes from preamp, I completely lost my effects loop (which sucks as I have a few pedals there which I like to use from time to time like delay/chorus).
I think I am going to try Mark V with 8 Ohm HotPlate if I can find one within the next couple of weeks. I have a suspicion that the 4 Ohm HotPlate I got, isn't 100% functioning - the bright/deep button don't seem to have any effect and also according to the on-line manual some lights supposed to be lit up during use - maybe that's why I am not getting good results with it, not sure.
I do like the sounds I get with Mark V and versatility it offers, but for foreseeable feature 90% of my playing time will involve headphone use and if I couldn't get the good results with Mark V, I'll probably have to send it back. Who knows, maybe they will add the recording out feature back in Mark V(b)?