Hello tonybelding,
The easiest way to determine which center to get (apart from the good advice given by others here) is room size and listening distance.
The VP100 and VP150 are tonally neutral and very similar. For rooms up to 2,200 cu. ft and sitting up to 10 or 12 feet away, the VP100 does a fine job.
If your room is larger or you sit farther back (or you have large floorstanding speakers and want to have similar power handling abilities in the center), get the VP150.
The stuff about sibilance is nonsense. I do extended listening tests to all of the Axiom speakers. They are neutral and balanced for rooms with normal domestic furnishings (rug or carpet on the floor, upholstered furniture, perhaps some bookcases or the like to break up reflections).
If the source material has been recorded with microphones with a presence peak in the midrange (not uncommon on CDs, and a few movies) the Axioms will reproduce it accurately. Don't expect a neutral linear uncolored loudspeaker to compensate for engineering screwups or bad recordings.
Soundtrack transfers to DVDs these days are not overly bright like some in the old days of laserdisc, where the THX curve was sometimes useful in cutting some treble. Nowadays the THX EQ isn't needed on the vast majority of Dolby Digital movie and TV show soundtracks.
See my articles in the Axiom Learning Center on Fine-Tuning center channel sound. It's important to experiment with placement in your room, which can be hugely influential on loudspeaker sound.
Oh, any decent brand of AV receiver, including your JVC, will drive 6-ohm speakers as easily as 8-ohm speakers. Only a 4-ohm speaker like the M80ti towers cause problems for some brands. For those, we recommend only Denon, Harman/Kardon, a few Yamahas, Rotel, B&K and NAD. Some new Pioneers, I'm told, will drive 4-ohm loads without overheating or shutting down. A 4-ohm speaker has less electrical resistance, hence more current (power) flows through the output stage, the transistors run hotter, and many brands (Sony, Kenwood, etc) can't handle it, so they shut down temporarily or go into current limiting, which limits power output.
Regards,
