Well the The Tekin is just a hair smaller than a Mamba Max ESC and lets just say that it is still big. Bigger than you think by there little square on their advertising.
Take those measurements and cut out a piece of paper or scrap lexan and lay it in your 12th scale. It will feel huge in there. I have the VFS Pro Comp in my 3.2R and the MRT MX PRO in my Gen X and I feel they are even a bit big when you add your capacitor.
So really I hope that the brushless peeps will get there stuff together to make a smaller footprint.
Although I think you won't really need the fan or heatsink on a brushless ESC running 4 cells as they were designed for 6 cells. Just a thinking if you don't need it why have it there? But I would have to check with the manufacturer about warranty issues. But if you want a ESC that will fit now and will soon be able to run the censored or senseless motors the Mamba is on point. I am thinking of trying it in my 3.2R, just have to solder on smaller wires as those huge wires can really mess with tweak. At least they seem they would do so....
OK my mind just keeps spitting out random info...........Oh wait I forgot my meds...Shhhh don't tell the wife..LOL
-Shookie <><