Hey Sampiek,
While I'm not too familiar with the Chaparrals, I know they are very good boats and I believe they have the old Sea Doo engines in them if I am correct, very good motors.
I guess it comes down to what you want to do? If you're in Chicago and want to hit lake Michigan, the 223 with the twins would be my go to. Bigger boat, slightly better ride and in the unfortunate event of an engine going down, you have another on the lake to get back (not that it happens that often). Towing, the 223 is heavier, a bit bigger. Engine maintenance... two vs one. Again, not that big of a deal, but oil changes (etc) will cost more if you take it in. I believe surfing would be about the same, both will throw a wake, the 223 a slightly larger one. Tubing, skiing, wake boarding is a wash, for the most part.
Size difference, well, two feet might not seem like a lot, but it's nice to have along with any extra storage. Ask anyone and one of the biggest things you should look for on a boat is storage. Everything you want to take for the day needs to be packed into that boat, again, if you have a bigger family or friends come along, the 223 would work a bit better.
Now, don't think the 203 is a slouch, it's a very good boat with plenty of power and storage. I was looking at one before I chose my Yamaha.
There are a lot of Chaparral owners on here, you might want to amend your forum headline to "New to Chaparral, please help" and they'll come to the rescue, good people on here and very knowledgeable.