Dave b and I seem to have similar feelings about the sound characteristics of some ARC amps, although I actually like the VTM200 amps quite a bit so long as they are partnered with the right system and speakers to balance their less tubey sound.
I guess if I had to pick between those two (VTM200 and REF300mkII) purely based on sonics I would choose the REF300mkII.
The other things you could consider are the VS115 or REF110, which may have plenty of power for your speakers. I did a quick check of the current iteration of the Verity Parsifal and they are 8 ohms nominal with a minimum impedance of 4 ohms. They are also pretty efficient at 89db. Without seeing actual measurement graphs I don't know if there are any difficult phase angles, but they appear easy to drive. I'm not sure if your version is the same or not.
The other thing you can do with 8ohm speakers is run two VS115's or REF110's in a balanced bridged or push pull configuration. I recently set up a system doing just that on Vandersteen 5A's with two REF110's and the results were incredible. So you could start with a single amplifier and see if it's enough power, and if not, just add a second one later. (Not recommended for 4 ohm speakers)
I guess my point here is that the VS115 and REF110 are both better sounding in nearly every qualitative way than the VTM200's and REF300mkII's except for power.
