I set my trackpad on a mouse pad that has a gel wrist rest on it. Made a big difference.I had the same idea so I bought a magic trackpad. Unfortunately, it forced my wrist into a weird position and I started getting RSI issues. It might be worth picking one up to see whether you have any issues or not. I'm tempted to buy a new desk so I can work out a way to make the magic trackpad work for me.
I'm curious to know the answer to this question, too. I've never once felt limited on OSX. It does everything I want it to. Being able to access the terminal is also incredibly useful. I don't feel 'sandboxed' at all.
I don't understand those who say Macs are locked down. That's crazy. I've customized mine like crazy. I have PC's in the house, but I do everything from my iMac. It hasn't limited me in any way.