The Aisin six speed shifts WAY better with the Motorcraft, the five speed somewhat better. Where I've found the largest difference is when the trans is cold. It was cranky when cold, and now I can barely tell the difference between cold and hot.
For some odd reason, the old Miatas hate RP products. Given that they make exceptional lubricants, many owners have tried their stuff with disappointing results, particularly in the transmission. Many report good results with Redline in the diff, and so I went with that and so far so good.
Lots of yanks on the Miata forum poo-poo the Bosch lights as inferior to the Cibies, but given that I drive the car summer only (long days) and the Bosch kit was easily available from Flyin' Miata, I didn't hesitate to go that route. In the end, I've been very pleased. The kit came complete and ready to go and the increase in visibility was dramatic.