I can shed a little light on this for you, might help you make a decision.
I have an '02 220 (just got done, literally, doing a top end / KIPS cleaning) with the following:
-Desert/rev pipe & aftermarket silencer
-35mm Carb (same size as the 200's), jetted to my liking
-Boyeson power reeds
-Modified the air box lid using the suggested method on this site
When I bought the bike about 10 months ago, it had the rev pipe, I added the other items as listed above. Most of the riding I do is tight, sometimes rocky terrain in the mountains. The rev pipe takes a little away at the bottom, but the combination of the reeds and larger bore carb (the 220's come with a 33mm carb) brings a little of that back. I really like my setup, it runs well in the woods and mountains, and then when I'm in south georgia with family/friends, I can really let it rip on the flatter/more open terrain.
Has the piston been replaced in your 220? There is a lot of chatter on the web (could just be from 1 person) regarding the 220's having suspect pistons - supposedly the skirt cracks/breaks and a fragment will fall down into the crankshaft area and cause big problems. The reality of it is, skirts break on all pistons/bikes, 2 stroke machines are just more prone to such.
I'm a sucker, I bought a piston set a few months ago and took mine down last weekend. I figured that for 135 big ones and some time, it would be a nice little insurance policy if the piston problem is indeed real.
On to the bike, I ride with guys that have 2 strokers, 4 stroke 250MX bikes, and bigger bore KTM enduros. I've never had an issue 'keeping' up with the crowd and find the handling/woods-worthiness of my KDX to rank up there.
Good luck with your decision, sorry to ramble on too long...