My friends here in the KC area use a mobile vet service for their small animals and are very happy with the service and the care. I think it's going to depend on the vet him/herself but for routine exams, shots and such I think there is no reason not to use a mobile vet - how convenient it would be for someone like you with several animals to transport!
As long as your pets are healthy and aren't going to need anything special, I think it's a great thing! I know mine are much calmer/happier in their own home.
My equine vet doesn't care for pets either other than he will euthanize them... my dog has terminal cancer, I own 44 acres, want to euthanize and bury him at home when the time comes so I asked as there are no mobile vets here.
I worked in a large multi Vet facility with a vet that also did private mobile work on the side. The great thing about her was that she also did in home Euthanasia, so people could say goodbye to their pets in the comfort of their own homes. She ended up getting so much clientele with the mobile stuff, that she left the practice. I think it's fantastic if you can find a great vet that offers that type of service.
And just to add I'll be using mobile vet -just- for routine exam and shots. For emergency/issues/pet fixing I have an awesome clinic I go to for number of years already (but it's not next to the house, so making 3 trips there takes quite a bit of time).
Joe -- I do not think it is a problem as long as she did not sign a 'non-competeition agreement' in a contract when she went to work for the clinic. Many practices from Vet to MD to Law practices have non-competition contracts. I'll bet the clinic she worked for will have one next time.