My experience is that there's enough registers on x64 to generate reasonable code, and that register renaming usually works well enough to make use of enough pipeline to be fast. I'd be curious to see real-world cases where it's a significant problem.
You wrote "Which makes a cleaner complier target than X86-64 with its scarcity of registers." - I'm just not seeing the problem. I don't like x64 that much, but I seriously doubt it's a meaningful issue for codegen these days.