If you're planning on a Cradle, better get it fast; it's on sale at the moment due to a clearance for whatever reason (hopefully Cradle isn't going out of business...).
Ra-Tech barrels are nice; look into the 6.03 Maple Leaf barrel though. Easier to maintain than the 6.01 and just as good for accuracy and range. I'm actually fairly tempted to get a VSR bucking and barrel hopup unit for more options... Also gotta get a new charging handle; I just snapped mine today
I found the MP5 Magpuls made it a bit of a pain in the ass to refill the mags with gas/CO2. Low quality ones tear when you push the pull tab out of the way to re-gas the mags.