I have the 55 remote. I really don't see any point to it if you have the steering wheel control adapter. It doesn't do anything with the D3 beyond that.
I guess if it was your only other-than-the-screen option, then maybe.....but still kinda pointless. Play, stop, source, mute, and volume work. If you are on a screen that allows for direct number entry, they work. But the enter button doesn't, so you still have to touch the screen when you are done inputing numbers.
If you really want it, I'll ship you mine for $10.
Someone posted elsewhere that the CD-SR1 remote works with the D3, despite Pioneer not listing them as compatible. I'm tempted, as it would give me the option to answer and hang up calls without removing my dummy face plate. But I haven't tried it yet, so I can't comment much on it.
I haven't seen the HD tuner module, but I am interested. XM is a joke for me, the sound quality isn't worth the cost of the tuner, let alone the monthly fee. So let me know how the HD turns out. I think we have about 12 HD stations in town.