If you are flushing, why use the expensive stuff? I'd flush till you are happy with the results, then do one more with the better stuff and run that.

 

In your situation I'd just keep using the cheap stuff. MaxLife D/M is a pretty good ATF, but I'd be hesitant to dump so much of it with drain'n'fills due to the price.

If you want, once you get the tranny clean, you can do a 'fluid exchange' (not really a flush) by changing all the fluid in one go. There's a writeup on here somewhere of how to do it, but essentially you disconnect the hoses to the transmission cooler, put one in an empty bucket, and put one in a bucket of brand new fancy ATF, and let the transmission's own pump change the old out for new.

 

No, IOW I'm stickin with and reccomending what I know works from true life experience. You can google all the facts you want about different lubricants and their manufacturers claims. If you believe in the stuff use it yourself. No need to discuss this any further.