The 700 would be fine in every way, unless you are looking for outright performance. It ought to run in the high 40s for top speed, and would have plenty of grunt to haul 4 people across just about any terrain. Now if all your friends have 900xp Ranger, or 1000 Can-am's you may wish for a bit more power to keep up. I have an 800 Odes, and we ride with some people in our group that have 570 Rangers, and they keep up just fine. The 1000 is physically bigger and would be more comfortable for 4.. ahem... "full size" Americans.
Depending on how you want to use it, would make the difference on whether to go to the 1000. If its normally you and one other, and you just like trail riding or running around, then the 700 is more than enough. If you always take 4, and you like running sand dunes, then you should get the 1000.
As far as reliability? It's a Honda. nuff said.
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