If it's in good shape, I probably would buy the Id.
The Id was my first playboat and there was a lot good about it --
From a river running standpoint, it has enough speed that it does quite well in class 4, even very big class 4, ..
AS LONG as you can deal with the fact that it is VERY slicey. You have to have very good edge control to keep from getting caught by cross currents and window-shaded.
I think this boat can teach you/train you to make really crisp eddy turns and watch your edges when you change directions in rapids - cause if you don't, you'll get chundered.
As a playboat, you know it's definitely not full-on. It's a bit long for looping, and many new-school hole tricks. Volume distribution is wrong for real aerial play.
But it has a very loose hull for a boat of its length, and surfs and spins really nicely on the right wave. Also, being so slicey, it is really good for flatwater cartwheels and is a stern-squirting machine.
Being an older boat, it will have harder/more durable plastic than current Dagger boats. My Rx isn't holding up nearly as well as my old Id, which I regret having sold a couple years ago.
But if you really want to playboat, I would buy a newer, shorter boat.
$200 for an Id in good shape is good deal, though, IMO ...