FYI: there is a lot of missing info with regards to the questions that will help forum users to better answer your concerns or might be answered by reviewing the FAQ, Premiere product page or the forums (such format you are using now, legacy requirements and what are your requirements going forward?)
Here is the readers digest version.
In terms of significant platform differences? where you'll see the difference is in the range of supported hardware (video cards, array controllers, audio cards, keyboard, mice. Professional add-in cards SDI cards, frame capture, etc generally have support by the vendors and feature parity between Windows & OS/X. If you use thunderbolt accessories, windows lags behind OS/X. 4k-6K workflows require more powerful CPU's for decoding, vendors of windows machine have more powerful machines than Apple.
In terms of codecs: There are some differences: pro-res are only outputtable on OS/X, quicktime on windows is 32 bit so there are output limitations on windows which are not present on OS/X as quicktime runtime is 64bit. Windows has their WMV which isn't available on OS/X.
Hope it helps.
Thank you StevRo,
That helps a lot. I use ProRes 422 quite a bit. I also work with 4k footage shot on a Red Epic frequently. I also use a hacked GH2 which shoots in AVCHD. I guess I am trying to decide how my work flow would improve by moving to PC. I'm also concerned about graphics on a PC vs a MAC. I read in another forum that graphics on a PC are some what limitied to the Animation codec if an alpha channel is desired.
Thank you again for your input. Making a switch from MAC to PC is a tough when I consider all the hard drives I have that are formated to MAC. I wish there was a good external hard drive solution that worked on both systems.