Well, let me first give a disclaimer. Our Gasgas EC200 is a '99. It's pristine and is set up very nicely. Also, my full time ride is a KTM200 although I ride the gasser a lot (my son's bike).
I am 44, been riding since 10, but most constistantly for the past 10 years. Race a few local enduros, but mostly lots of trail riding. Solid B rider, but can hang with the A pack. 5' 10" 220 lbs. All of my riding is NW woods. Mix of very tight singletrack (see vid, me) and some more flowing quad width (see additional vid, not me). Since it's the NW we have LOTS of rocks and roots and it's often wet. We also have some very steep terrain.
http://m.youtube.com/watch?v=d1wolKqZRy8
http://m.youtube.com/watch?v=quW_d2XGsXY
I've owned many bikes: KTM 300, 250, 200; Gasgas 300, 250, 200; Yamaha wr450, wr250f
The 200 is simply easier to go faster on. I know weight is such a subjective matter, especially when talking about dirt bikes, but the 200 feels amazingly light when compared with the larger cc's. It makes riding in the woods a lot less tiring and you can change direction so easy. It makes perfect power for woods riding. They still lug very well and you can ride a gear high all day, but the power won't wear you out. You feel like you can push the bike hard rather than holding it back. The handling is where it really shines and it slices through the woods like a knife. To me, if most of your riding is in 2nd-3rd gear, you'll love a 200. If you ride more open or flowing terrain, then the 250 or 300 is more at home.
I know a lot of people are concerned about the 200's ability to climb. First, if we all had bikes just for hill climbing then we'd all ride CR500's! The 200 has made every nasty, rocky, root infested climb my 250 and 300 made, and it does it with less effort. The power is going straight to the ground with less wheel spin and the light weight makes it easy to maneuver. I ride a ton with my brother who rides an EC250 and I made climbs last year that he did and a few he didn't.
The one drawback is deflection in the rocks and roots. Because they simply are lighter, they tend to deflect a bit more than a larger bike. I have the suspension revalved and set up for me and us a Scott's which help a ton, but there is that aspect to riding a lighter bike.
If money were no object I'd go buy a new Gasgas EC200. Hope they don't stop bringing them here to the US!
Sorry for the hijack and long winded post