as the only other tool... err... toole on the board, i feel i must help
somebody had just posted a $90 mod which allows you to tweak your line preassure which will affect overall performance on the level of shift firmness, tq converter lockup, mild heat control, etc... this is basically what the tranny features of the Diablo chip do, but it is ONLY the line preassure... none of the shift points, etc will be changed.
The only other options are rebuilding the trans itself.
Level 10 has a full build kit which costs $3200 installed and you have to get a trans to them on the front end as they do not provided initial cores. you can do partial builds (just clutches, or just tq converter) but the entire build is the best bet in the long run.
Performance Automatic is in the process of developing an ATX trans kit. for now they have only finished the "race overhaul" which replaces all the clutches, bands, etc... this will not do a whole lot on it's own. Though, the clutches are our weakest link (especially 3rd gear) it wont do much to just replace the clutches. it'll prolong the tranny life, but there is no sense in having clutces & bands that handle high power and keeping the stock tq converter that shuts down at about 130hp...
thats just some general info.
we have had some extremely in depth conversations on this and what our options are over the past few months... search for keyword ATX in this forum and you should be able to get some other views from many of the boards ATX owners.