I'd say in terms of the amount of sounds available they are about the same. The deep impact has the HUGE bonus that once you find a good sound you can save it, along with a few (9 if I recall???) and use them during a gig by cycling through them with the foot switch. The EHX is one sound, then change all your settings for another sound, but I do find you can fine tune a specific sound a little better.
Having said that, the EHX does cut though much better and it doesn't suck your tone like I used to find the Deep Impact did.
If you have a Deep Impact though, I would be reluctant to swap it for anything that is not bloody fantastic as getting another one if you change your mind will be no easy task!
P.S. EHX definitely has the better Octaver sound!