My two cents...
It seems to me that the SL1200/1210 offers such good potential performance because its base engineering is of a quality that would usually cost the end user a lot more money. Because they were produced in such large numbers and sold by the shedload to budding DJ's in the last couple of decades, the per-unit costs could be kept lower.
Most low volume turntable manufacturers would simply have found it too cost-prohibitive to produce something like that. Same principle with the Garrard 301 and 401. Look at what a 501 costs these days. 
I really love the look of the SL1200 actually, I had a pair in the 90's when I wanted to get into DJ-ing like everyone else. The DJ-ing thing kinda faded but I didn't get over the vinyl addiction! If I'd known at the time what a tricked up 1200 was capable of, I might never have gone down the route I went down. But that was over a decade ago.
Currently Listening On:
Turntable: Garrard 301 (solid chassis rebuild), SMD reference plinth
Arm: Audio Origami PU7 (12")
Cartridge: Van den Hul Black Beauty
Phono: Whest PS30RDT
Preamp: Scratch built AMB a24/LCDuino/d1/d2, fully balanced
Power amp: Transcendent 15W "Son Of Beast" OTL with upgraded Takman/Mills/ClarityCap MR/Jensen components in signal path
Loudspeakers: Steve Cresswell's old Metronomes