There is no exact info at the moment, "omgmog" on the Dingoonity boards is putting together a pretty detailed review. He's taken a unit apart and he thinks that the cpu speed may only be 200Mhz. I've seen a PDF regarding the SPMP8016A (which may be the chipset used in the Letcool ), this document states that the cpu speed is 270Mhz. However it also states that the DSP cpu is 324Mhz.
The Dingo has 1 cpu which is 336Mhz, this can overclock to 400Mhz though. So the Dingo's main cpu is faster which means "quick and dirty" ports will run better. Anything on the letcool is going to take alittle more work to get running at a decent speed.
I just see the Letcool pretty much like a GP2x, just with better battery life and good controls. It doesn't run Linux at the moment but I'm sure some clever bugger will get it running at some point.