Kurt, M105/Cyan is fine, but as with any glass polishing, don't expect a dramatic difference if the glass is in bad shape. I say this to stress the fact that you do not want to use much pressure when polishing glass, even with M105, or you could cause swirls and scratches. Keep pressure light and slow movements, and keep the glass somewhat lubricated while polishing (minimize "dry polishing"), and the working area small. A few passes and it is going to be as good as it will ever be.
And yes, Aquapel is legit, and does not compare to Rain-X. You'll love it!
As as general Aquapel advice to all, there is really no need to "clean" the glass with a polish before applying aquapel. Glass Cleaner works fine, but the solvents in the Aquapel applicator will eat through anything on the glass. I have applied Aquapel onto a dirty and damp windshield, used the applicator as a scrubber, and wiped off (was in a pinch towing at night). Worked fine, and lasted a few months as usual.
Cleaning the glass will make application smoother and easier, and polishing will make the glass more clear and removes any water deposits or etching. Which will all make the glass look much better even before the aquapel. With nice, clean glass I have used one applicator for both the windshield and backlight (rear glass) with decent enough coverage on the rear glass to make a nice difference. I was not able to do it, however, on my truck since the windshield is so freaky big.
But the reality is that Aquapel is a temporary coating, just like wax. Even if the conditions are not ideal, any application will be quite effective, and more effective than no application. I'd prefer to get the aquapel on the windshield ASAP rather than wait for an order and a free weekend if I did not have anything to polish with. I would just re-apply whenever (straight on, no real need to strip the previous Aquapel off - again, solvents will eat through anything). So even for people who do not want to have to polish and prep their glass I would strongly recommend an application of Aquapel. It will last plenty long, and work just as good.
We have clients who buy the stuff in bulk and use it for their glass showers, mirrors, and other glass around the house. Its some really good stuff.