The long memory (as long as you don't require max. sample rate) helps with this, so peak detect won't be as necessary (it can just store all the samples). If you do require peak detect, check if it supports sample rates all the way up to 1GS/s. On some scopes, peak detect doesn't work at the highest sampling rates, which makes it much less useful in my opinion. Also check out the competing Instek model, it could be superior in this application (supports long memory even at 1GS/s if I recall correctly).