I'd love an A4000 myself but I can't justify paying that much for old hardware...
I'd second the A1200 suggestion, you can do all the things your 2000 can do and more, especially if you like to use DPaint, you can get DPaint IV and draw with AGA graphics. It also takes up so much less space. But if someone you know is offering you an A4000 at a good price, well I'd be sorely tempted put it that way.