Barry, I recommend retrieving with a metal peel for two reasons:
1. I've given a lot of thought as to why wood peels are more effective at launching than metal ones and my prevailing theory is that the porosity of the wood allows it to grab lots of flour, which in turn, creates a bed of flour for the skin to slide on. This flour grabbing trait makes it ideal for launching, but, unless you wipe the peel vigorously, there's a good chance you might get some raw flour on the cooked pizza, which, imo, is to be avoided.
2. Although, over time, as you launch more and more pies, you'll eventually stop making errors/seeing calzones, cheese and sauce are going to occasionally get on the stone, either by boilovers, holes in the undercrust or an errant piece of cheese on the rim. Just as you don't want to use vegetable or nut oils to season a wood peel, you also don't want to get butterfat or pork fat on it, because that, too, will go rancid.
I guess, if you wipe the peel carefully, with a cloth, between launching and retrieving, go with a thickness factor that never produces a hole and position your sauce and toppings in such a way that you never have a boilover, then, using the same peel should be fine. I guess, also, if you make your own peels, you can worry less about the boilovers and just replace them when they absorb too much fat.
At the end of the day, though, imo, one metal peel for retrieving and one wood peel for launching is the simplest and most hassle free approach.
