I have the Armorsuit (both screen and body protectors). They all use mostly the same material. All are kind of a pain to put on, but I can say that now that it's on I can't even really tell it's there. And they have great customer service at Armorsuit. I often run with the watch and wash it off in the sink and wear it all day long and I haven't had any issues with the screen protector lifting off at all for the last month. The trick is getting it on correctly so that no part of the protector overlaps the case (can be tricky because initially the sides and corners won't stay down and it slides around a lot if you wet it well). And then you have to make sure it adheres properly around the edges. The trick I use is to let it dry a bit, for maybe a half hour, and then I take plastic Saran wrap and wrap it around the watch. This allows me to kind of pull tightly around all the corners and sides and then twist the plastic wrap behind the watch to keep all the corners in place while it dries for a day or so. Then I take the plastic wrap off, or loosen it a bit, so that it can cure further (if you wrap too tightly, it won't always dry as well because there isn't enough air flow).
But now that you have AC+, maybe don't even worry about it. Just enjoy the watch and use it well and perhaps get a replacement down the road.
And thanks for the reminder about AC+. I still needed to add it to mine. Tried the other day and the Apple site kept taking me to the British site and asking me to pay in Pounds. Weird. Couldn't get it to work right. Today I had no issues. Was able to run diagnostics through their site and purchase online.