I had a hip replaced in Sept of '11. I fractured it in a cycling accident and because of where the break was there was a risk of necrosis in the ball of the hip so it couldn't be repaired. In any event it was replaced and I was back on the trainer in two about two weeks. I did spend a week in rehab and worked the bejesus out of it in PT three times a week and on my own every day. IIRC I was back on the road in about two months.
I never considered a recumbent but at first I was on a Giant Tempo (spin bike) and that had an easy step through from there it was the road bike on the trainer then back on the road.
My surgeon felt cycling was a great activity for rehab since it's not weightbearing and good for increasing circulation. He told me the most important thing to extend the life of the replacement was to keep my weight down to limit the load on the joint. If you want a good result you have to really be diligent about the rehab. The way I see it is the surgeon does his part in the OR after that it's your responsibility to take over and manage the second part of the process.