How good is the Technics 1200 Mk2 with all the KAb upgrades?

Not as good as my VPI.

I've heard them sound great. There are other upgrades that also take it to a higher level including bearing upgrade, platter upgrade(Mike New from Australia does what are some of the best, external power supply and Isanoe feet. 
Tonearm upgrades are also good improvements over even the rewired original if you are inclined to do so. With Transfi Terminator arm, a friend has better performance than his previously owned ELP laser table and his VPI Aries. 
Check out theartofsound British forum, the section called Techiepedia for many 1200 tweakers' experiences. 
http://theartofsound.net/forum/forumdisplay.php?46-The-Techiepedia
Cheers,
Spencer

Great find.  I cannot imagine having such a jewel on hand and forgetting about it.
i have the same rig.  Love it!  My VPI (classic 4) ls wonderful, but the 1200 MK2 is much easier to use.

I have a stock 1200 mk2 and love it. In my humble opinion, buy a reasonable cartridge and let it rip. 

Mine is carefree, reliable, and trustworthy. No fiddling and or second guessing required. 

I don't enjoy calibrating equipment- I just want to play records and enjoy my music.

If you think along those lines- you may have a keeper!

Hope you enjoy your Technics!

I mounted a Jelco 750D on my SL1210 via a wooden armboard sourced from a Technics guru on Fleabay.  I have no complants about the Technics arms, they are quite good but the Jelco just brought a little more refinement to the mix with the same carts. It was readily apparent since most of my LPs are classical. Smoother string tone.