In terms of returning to normal, it has varied, normally around lenght of usage with the pump. My OH is smooth also. The main thing to remember is everyone is individual, and circumstances always different - so what works/happens for me and OH may be completely irrelevant for you.
My advice is good lube, take your time, let her get used to the sucking sensation and pressure, and build on it. If you're in control of the pump, communication is key and slowly does it - half a pump can be the difference between 'holllly sh!t thats awesome' and 'get that frigging thing off me, its sucking me inside out'. It's not the quickest thing to do, and patience is comfort. I use a lot when I tie the OH up and have my way with her, I know her reactions well enough to see when we're hitting limits.
If you are both keen, best thing is trial and error. Try it for a short while first and see what results you get. Make sure she doesn't have a lycra/gym session planned in the morning to be safe :-)
In terms of short or long term issues, none that we have come across - but that doesn't mean there isn't, I am sure there are others more experienced with them that maybe able to answer better.