Ken, I greatly understand what you are experiencing, what has helped me after much trial, is to first get or make an image of a grey scale - i just made one in Paint.net, its 4 boxes side by side the leftmost is white and the rightmost is black, with two intermediate shades of grey in between.
i have given up on the grey-scale setting in T2 for the moment and gone back to dithered at a high resolution.
then in t2, figure out what speeds and powers get you the best result, where you can see 4 different blocks,
this itself is tricky because you'll find that after a certain power level the wood response goes up dramatically and you get too burnt on the black.
what i try and do is find the highest power level that does not actually mark the wood, and use that is the low (off) power.
you will most likely need to lower the speed, you can check this by looking at the borders of the squares (which are thin black lines) on your results, if you can't get clear borders then the laser is moving too fast.
my best settings for wood seem to be around power 125/230, speed 700-1000, resolution .03-.05
another tip ive found is that if you find settings that work well, and on the next image you decide to change the resolution, you will need to find new settings for the other parameters, lowering the resolution makes the result much hotter (darker)
don't go lower than .03 - .04 if you do large images because it will crash T2