I often record songs with drums samples or drum machines, but it's usually my band and even then different drummers can have very different feelings -- ranging from being "replaced" by a machine to seeing the electronics as another tool at their disposal. Some drummers won't even use a metronome tutt, and some drummers like a good beat
regardless of what instrument was used to create it.
If you're looking for precedent there are LOTS of examples of recordings of bands using drum machines. You need only watch
Behind the Music to learn that the drum sound on Def Leppard's album
Pyromania is an Alesis HR-16. Hybrids are also popular, e.g. Larry Mullen Jr. of U2: He often uses a drum machine to provide a tempo and accompaniment sounds, like tambourine or other percussion over which he plays the drum set. Also, it seems quite obvious to me that many "metal" songs use samples/drum machines -- including many of Motley Crue's (I just checked a few clips on iTunes and I'm quite convinced). Even a lot of country music nowadays is recorded with samples. And remember, just because you see a drummer playing in the video doesn't mean the recording is acoustic drums.
*steps down from soapbox*
Keith is right -- Obviously, you should talk to the band and the drummer about this before you do give them a mix with your drum part. You could offer the samples as an option, but the final decision has to be with the band -- they should be getting what they are paying for. (Unless you're a high-price engineer who has a contract giving you right of refusal.)
If you think you need to mention this issue, if he's your friend, it might actually be easier to bring up. Just explain the situation to him the way you explained it to us. Prepare the mix with
his drums first, and a back-up mix with the electronic drums. Play the mix with his drums for them first, then if it feels appropriate you could mention the other option.
Also, if neither of those seems like a good option, depending on your schedule and resources, perhaps you could try recording the drums again (maybe try some better mics or a bigger room).
Whatever happens I hope you let us know how the situtation turns out.