07-02-08: TpsonicFully upgrading an RB250 or RB300 runs the cost up to $800-900, (which includes all the mods you mentioned, but sandblasts off the overdamping powder coat and puts slots in the tube to break up resonances), but you're still stuck with the OEM bearings, which I understand is the RB250-300's achilles heel.
Origin Live arms are a drop-in replacement.
The Origin Live Silver incorporates all the improvements on an arm with (they claim) much improved bearings and OL's own VTA adjustment collar at $1050.
At the $200 difference, I'd probably spring for the Silver.