I think the DSI2 has a slightly larger chip size and more sensitivity, meaning it will pick up objects a lot easier. Just Google for specs on each one and that should tell you what you need to know.
Also, watch out for the Meade bashers that lurk around this site, telling all how bad Meade stuff is, but not realizing that due to innovations by Meade, they are enjoying high quality telescopes at a great price in other brands.
There is a lot of cameras out there, go through the imaging threads and see what people are using, make your mind up, stick to your guns and learn to get the best out of your equipment before you upgrade.
