This is a toughy. I am happy to see that you like Nu Finish so much but there are a few things about the product that I personally didn't like.
On the Polish 16oz liquid.
I have used this stuff since the early 90's and though good for water beading, it is a PITA to get off the black trim. I mean it stains pretty bad. It also is very easy to over apply causing for allot of powder residue which creates more work to clean up, even with micro fiber towels.
The "Cling" spray wax:
I didnt' like this stuff either. On a Red car it streaks like a Mutha and is a PITA to wipe off unless you instantly wipe it off.
Also, with the Volvo, (nice car by the way) you only washed that car 4 times in 3 months?? So it must not get very dirty, which may contribute to the enhanced duribility. I live in an agricultural area where bugs are flying all over the place. You have to wash your car all the time here and keep allot of wax on the car so the bugs wipe off easy. I also live in the Desert where 120F + temps are common.
Of Note:
While in College, I did a thesus in 1992 on Polishes for Autoes, where I tested the top polishes/waxes of the era they included:
1) Nu Finish
2) Turtle Wax 2001
3) Mothers Carnuba Wax
4) Mequiers Cleaner Wax
5) Zymol liquid
Of the 5 in my 6 mont study of having painted panels sitting outside in the sun, and rain, etc the Nu Finish was the clear victor. How much that says today?? May be a different story.
If you find a product you like USE IT and don't let anyone steer you away.
Jeff