When I was considering that same question with my Technics SL1210, I was actually looking at installing an SME V onto the Technics. There are a couple of DJ companies that do these modification to SL1200's. If you are worried about the RB300 being up to the task, then step up to the SME armboard mod. Or get a Michell Technoarm or Origin Silver.
I decided I didn't want to work that hard with modifications and bought a Funk Vector (another completely different version of a direct drive output due to the three pulleys). My stock SL1210M5G with upgrade arm and cabling didn't let my Shelter 501 MkII $850 show it's best, when compared to my friend Audio Technica ML440a $99 cart, and hence why I was either going to change arms (I know you can do KAB damping and rewiring) and do the KAB powersupply mod to get the most out of my cart. My Funk Vector Table with the RB300 (bought a Michell Technoweight since the stock one sucks after using the Technics arm) was amazing step up from my SL1210M5G with the same cart and same phono preamp in my system and in my mind a giant slayer. Now I want to upgrade to the newer Funk Saffire so I can go up to a Graham Phantom Arm or a TW Acustic Raven One.
I still miss hitting the killer Start button on the Technics, and the non-audiophile speed strobes and popup drop light.. But now I can concentrate on finding new cool vinyl instead of tweaking.
The low start price and tweak ability (step by step) makes the SL1200 a winner if you can't go big (Throwing money at the problem doesn't mean you will get better results, my Funk has surpassed a lot of 5k tables and is a giant killer in my opinion like the Technics is in it's price range)
