Going back to Windows?!... Crazy.
I would argue OS X is supported - especially around here
... free... and way more effective.
How long til we see you back here
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This goes without saying, but don't choose on price if at all possible... Get the tool(s) that works best for you. Efficiency and lack of frustration are likely worth whatever they're asking IMHO.
I will be looking at LR6 when it lands, but even though I have a CS subscription through work and can use LR at no cost to me, I may still gladly pay Phase One $10/month or $300 for their tool because I enjoy working with it a lot. We'll see... I'm not making any commitments just yet.