Hi xsb,
Once the SL-1210 has been fully KAB-modified, and you fit a decent cartridge, there's not much difference in performance when compared to an SP-10. I know because I've recently compared my KAB-modified SL-1210/Denon DL-103 Pro set-up to an SP-10 with an SME V/Audio Note Io, in a Sterling Broadcast plinth, and whilst the SP-10 was better, the difference was fairly marginal and not what might be expected given the SP10's reputation.
Does this mean that the SP10 isn't as good as its revered reputation suggests? No definitely not - it's an awesome T/T. What it shows is just how good a fully KAB-modified SL-1210 is!!
Oh and to answer your question, yes the DL-103R works great with the SL-1200/1210 once some small modifications have been carried out. I have a standard 103, a 103R, and a 103 Pro, and they all works superbly on my 1210.
Marco.