My opinion of Royal Purple (gear oil only, I haven't used the motor oil in awhile) is largely the same, but I have been consistent with it for two reasons:
1. It is available on shelves near me
2. It is priced similarly to the other gear oils near me. eg. Royal Purple is $25 per quart. 1 quart Castrol is $22, Pennzoil is $25.
I originally picked it because www.rx7club.com
has many threads about how conventional (and some synthetics, such as Mobil 1) in the transmission cause some notchiness. Our transmissions are known for that, and Royal Purple, Redline MT-90, and Amsoil seem to be known for reducing it. Why Mobil has not helped the notchiness (though this observation is entirely subjective) is unknown. Royal Purple is the only one of those brands sold near me, and the cheapest. Ordering it on Amazon is even more expensive, strangely. Synchromax has also been really good in my Celica, although of course that is a different car and a different product.
I last switched from the unknown fluid the previous owner used to Royal Purple, but that transmission was on it's way out anyways so I should've just saved my money. It was definitely better than the old fluid in there, but what I'm not sure of is whether it would be better than a store brand synthetic.
The pragmatist in me says to go with store brand and not worry about it, but the other side of me says "Pay for the right product the first time or pay twice" and tells me to just get the Royal Purple that should (in theory) be ideal.
EDIT: I've looked into it further, and the store brand fluid is made by Shell for Canadian Tire and includes the LSD friction modifiers. So it is a $40 savings, and a name brand without the label. I'm going to give it a shot, will report back once my car is reassembled and I have some subjective results.