I've shied away from Microsoft licensing because it seemed complex. But looking at:
it shows just 3 types of software license - FPP, open, open with SA. There's also OEM, at least for the OS (is there an OEM CAL?). Anyway, this page seems to summarize things easliy - open's (only?) benefit is the electronic license? Yes there's transferability, like FPP, which you don't have with OEM. But is that it?
I thought there were more advantages? But at least on this page, open is cheaper than FPP. Why would someone buy FPP then? convenience? It's easier to order from buy.com vs a LVR.
SA gets lots more benefits, but adds to the cost.
OEM seems like the simplist - buy it with the server and be done with it? Yeah, you can't transfter it, and yeah, you have the paper license, but you have $$ in your pocket?