No support. Reason - 1.8+ compatible or not, we want everyone to be able to pvp the same. Some people may prefer 1.8 to pvp, but then they can't block hit? Some plugins won't be compatible. For example, when you have a texture pack not made for a higher or lower version. There will be glitches. I doubt this will ever happen. No support. EDIT: As said above, people may be wanting to play the new version of MC (1.8+ or 1.9+) If other popular pvp servers have 1.7 pvp, then go play there instead... Simple.
They're resetting a lot of things anyways, I doubt they'll care about going down to 1.7. They're resetting for a better start. Not to throw them baxk down.
You can make it support 1.7 - 1.9 there's a big server doing this but I don't think I can name it "Somtimes you have to take a step back to move forward."
No Support. Reasons by @NoMoreSanity. And 1.7 has no cool-down delay, Which means that people in 1.8-1.10 would have a lower advantage. Also, 1.7 enchantment levels are stronger which would also leave others to a lower advantage. I don't think this is even possible. How would you connect to OP PvP if your in 1.8-1.10 in the lobby?
No sense at all, there's lots of servers with 1.7 / 1.8 there's no difference in enchantements and what do you mean by cooldown delay?
Its not that I'm bad (in fact I'm one of the best PvPers on OP PvP) i just don't think this is even possible.. You also can't downgrade a server from its original place.