i think spaying is a more difficult procedure than neutering... but i'll give my input anyway... Kash got neutered on Thursday and he is 2.7 lbs... my vet uses isoflurane... but they still have to use a different medication to sedate the dog, and i requested ProPoFlo. it costs extra, but it's safer for the dog... isoflurane is the gas anethesia used to keep the dog sleeping after he/she has already been sedated.
Kash is already back to normal. he's sitting behind me on my chair chewing on an empty pill bottle... throroughly rinsed out, of course.
i think your pups (especially Lexie) will do great! maybe your vet just isn't confident in what he/she can do? i would be upset (like you were) if the vet was going into the whole procedure
expecting failure. ever heard of the saying, "if you think you're going to fail, you will??" well, that's actually only ever said for taking tests in school, lol. but you get what i'm trying to say. the vet should keep a positive mindset... but who am i to say that since i'm not remotely close to being any sort of doctor. maybe he has to prepare you for the worst JUST INCASE. that way he can say he warned you??
ack, i don't know... i'm rambling now. do what's in your heart.
good luck!