I have a mac mini and 2 pc workstations. Depending on the client I deliver either Avid DNxHD for broadcast (which MTV uses) which is a direct render from AE; lossless tiff or EXR sequences. But primarily DNX. For footage that is say 400 x 500 for an element I just use the larger DNX presets and crop in. It's not ideal but it works.
On the mac side it is pretty trivial for me to transcode from lossless Avid 4444 or qt 10bit on the pc side into prores on the mac mini. I have everything networked together and file transfers are instantaneous. I have never had problems with that work flow. But I guess if you are delivering huge final renders how that could slow you down transcoding everything.
Interesting side note, Avid DNxHD can be compressed almost 300% using a zip file. So I will transcode a 5 GB lossless DNX animation, zip it into a 1.75 gb file for upload, and it takes less than half the time to upload.