A question right up my alley. I own both an '09 Vector GT and an '09 Apex LTX GT. Rode them both for a week between 12/26 and 1/2.
The Apex motor is silky smooth and the ride is 2nd to none the way I have it setup. The ride was SO good, the wife only wanted to ride the LTX Apex, so I actually spent more time on the Vector. She claimed the handling was more predictable on the Apex with triple points vs. the factory carbides I haven't switched out yet on the Vector. I have shims on the Vector and I thought it handles real nice for the factory 4" carbides, but she didn't like the feel. I think the Vector is more nimble to trail ride than the Apex, but I'm more aggresive of a rider than her. Even the kid liked riding the Apex. I felt like they weren't showing the Vector enough love because I did some long rides on my own and I never got sore once last week, which is unusual for me. I'm amazed by the rear skids and how they soak up bumps - on both these sleds.
As for power, the Vector can do just about anything on a trail, corner to corner, that an Apex can do. I was surprised at how little difference there was in low end, and mid-range acceleration between the Vector and Apex. The difference is, the Apex isn't even working at trail speeds, it cruises, so you know theres alot there on top end. I just didn't get to hit a lake to try it out yet. Had them both up to 90 max, on the trail, quite effortlessly I might add. I really thought I'd feel more immediate punch at trail speeds from the Apex, but don't get me wrong, its still fun and quick. But the Vector has one strong motor in it for a quote, "120 HP sled".
In my opinion, if you don't need to win races on lakes, or don't ride with guys that run 75 - 80 on flat, straight trails in the UP for mile after mile, then just get the Vector and forget about it!