I'll start off by saying I don't have much experience in tanks but have RC experience in cars/crawelers. Read what I have below with that in mind.

I bought the Clark 60 series about a year or so ago but have only had it running for the last 8 months approximately. I originally bought it due to the fact it had programmable sound and proportional smoke. It also had the ability to support BB function. It also had the plus of being fairly inexpensive compare to the other guys. It is currently installed in a Taigen Mid Production Tiger 1 BB. Being quite the heavy tank it has performed well and no issues so far. I am actually in the process of converting it to IR function. Here is my pro's and con's list so far, as well as some recommendations. Please note that this list does not mean to compare to other boards as I don't have much knowledge or any experience with them.

Pro's:
BB Support
380 Can motor support AND 540 can motor support
3S Lipo Support
Lipo Cut off support
Various IR protocol support
Reasonable price
Good customer support (once you get past the translated material)
6+ channel support with appropriate programming
IR programming of the card with correct hardware

Con's:
To program the sound you need additional hardware and software (available from Clark and DKLM), this is different than the hardware needed for just general programming of the card
To change the number of channels being used you need to basically send it back to Clark for reprogramming
Information and Manuals take a bit of reading and re-reading to get around the translation
No hard copy of a manual

Recommendations:
Buy both the IR programming kit and sound programming kit when you buy the unit.
Try and buy a TK60 programmed to the number of channels you want to use (some vendors will do this for you) so you don't have to send it out to be enabled for more channels
Enjoy it!

Hope this helps you!