I'm playing through a Fender MH412ST (4 G12K-100s) and it's the size of the Recto Standard Straight cab. The MKIV through this sized cab sound massive and very tight. If I want it to sound looser, then I dial in more bass on the preamp side. These speakers are voiced on the neutral side and don't distort at stage volume, so with V30s, your mileage may vary.
This is just to say that a larger cab will sound larger and a smaller cab, smaller. The great thing about the MKIV is the fact that you can decide how loose or tight the tone will be. Anyone that says a MKIV can't be ultra tight (or needs a boost to get uber saturated) has a defective amp or can't set their's up.