There is an open debate around about how much is enough on the BMD forum, my solution is the Hyper Deck 2.
There are other more sophisticated devices, all well above the $1500 US price range however, in bang for buck the Codec in the BMD relies on AVID's DNxHD, which according to a couple of luminaries I discussed it with, will perform better in AE, alongside PP versus Pro Res. I'll take their word for it.
BMD also uses the ProRes codec now and is set to receive with bridging software like MAC Drive Pro.
Drive space is the issue, the read out from CS5.5 for me indicates capture at 10 bit 4.2.2, 29.97fps.