With the 2000 series I would definately not go with the 2 channel Version, as the digital channels (which can be used after hacking or purchasing the MSO package) does not allow any decoding, thus for decoding you need 4 analog channels.
Also it turned out, you will have a hard time to sell a 2-channel 2000series (or 3000series) later.
However, a 4-channel 2000series is OK.
But consider this: As the 2-channel versions (2000 or 3000 series) are hard to sell, you might be able to make a bargain on a 3000series with 2 channels. Here, all 16 digital channels can be used for decoding, triggering etc, thus the 2 missing analog channels might not become a problem for you.