According to the specs the TA30 is more efficient at high mode when the stated runtime with 225lm is twice than TA20 with 50% more battery capacity. I guess that the true difference isn't that big, however.
In some review they measured the runtime to quite exactly 3hours at high mode for TA30. TK10 with the same brightness and battery configuration as TA20 has slightly more than 1,5 hours runtime at 225lm, and if they both have the same XR-E Q5 LED I guess that TA20 has same runtime as TK10. TA30 is more efficient at high mode anyway.
If my lightmeter is correct as well my TK10 and TA30 have exactly 1/5 of the output at the 60lm mode than 225lm. Both has exactly the same output at 225lm mode which seems to show that the 60lm mode is around 45lm. The question then is if mid mode of TA20 stated at 50lm is 40lm or less, I don't know.
I think that TA30 is a very good choice if you mainly want to use the 225lm mode. But I would prefer a mid mode with twice the brightness as the actual, 2/5 of high instead of 1/5.
one thing more about the TA30. I own one and it can run using the following cells:
3xCR123/RCR123
2x17500
2x14500
so you have a wider choice of cells to use. i did not notice (to my untrained eye) any difference in output when using 17500s instead of CR123s
I tried my TA30 with 2xAA, and it worked also, but with a very low (but still useful) brightness...
Regards, Patric