For all intents and purposes, both the split and single piece polyurethane bushings will be permanent replacements. I did a lot of looking before I replaced mine, and didn't see any accounts of them needing to be replaced. I did find a number of reviews say that the OEM bushings, however, could fail within the first few thousand miles. Manufacturers may offer lifetime warranties, but you'll still need to put in the elbow grease to get them off and on again, probably spring for the shipping, and be without control arms for however long replacements take to arrive.
If you go for the polyurethanes, be sure to grease them or they squeak like crazy. I used
Energy Suspension's grease since it's supposed to be very resilient and not wash off. The biggest problem with the polyurethane solution is you have to get the rubber bushings pressed out by a shop (some people have cut them out too), but it sounds like that may not be a problem for you.