Quick question

Is there any difference between the Acekard 2.1 and the Acekard 2i, other than the DSi support? And does AKAIO work on 2.1?

They are the same thing except the DSi thing, and AKAIO works on most AceKards that are not fake.

So if i have a DSL and i buy the 2.1 because it's cheaper, i won't miss out on any kind of compatibility or anything, will i?

Nope.