Thoughts on 64-bit-only for Firefox Beta, Dev, Nightly and Thunderbird Beta

I recently switched the Google Chrome Portable Beta and Dev channels to 64-bit from 32-bit. I did this as it's currently not a dual mode 32-bit + 64-bit app due to the touchy launcher and portablization. I'm considering switching Firefox's Beta, Dev, and Nightly channels as well as Thunderbird's Beta channel to 64-bit only. It's currently a dual mode app, but I'm wagering than anyone wanting to test out upcoming features is probably not using an old Windows 32-bit machine. This would save on build and upload time. Is anyone out there still using a 32-bit Windows and using one of these channels? Any other thoughts?

Please note that this will not affect Stable of either app. They remain dual mode. Nor is this for discussion of wider 64-bit policy.