I am interested.

 

I learned about this device on this forum and decided to try it.

Short answer:
Works great! You won't be disappointed. About a 4 hour job including all the tool building and only moderate technical skills needed. Hardest part was shortening the hex wrench because that is very hard steel and I used up a bunch of grinding heads on my Dremel.
The guidance on this thread is very good.

Longer answer:
Before I bought this device I decided to drain and replace my trans fluid after purchasing my XJ8 used and not knowing how recently it had been replaced. When I started the job I had the car flat and level and decided to start by removing the fill plug. When I removed the fill plug a whole bunch of fluid came out. That told me that the guidance to fill only to this plug was possibly wrong. I would need to do that and then a bit more to get back to where it had been originally. So when I refilled the transmission I tilted the car up on the right side to add a bit more fluid. Well, that was too much extra fluid. The transmission had some problem shifting gears. So I drained off the extra to go back to the original fill mark as per spec. It worked, but I could hear a slushing sound when getting up to speed when cold.

I then purchased and installed this device and then added fluid a little at a time and driving it for a day to see that things were still good. Then added more and tried again. It is perfect now. No shifting problems and no more slushing sound.

 

I am interested, very.