The choice is yours of course.
I have tried the rattle cans SEM and the Stewart System. I decided against both... Havent tried P60G2.
This is just my experience...So take it with a grain of salt.
Stewart arrived in unusable condition twice. I talked to the manufacturer and it looked like it doesn't deal well with cold and I was ordering this stuff in the winter. Service was great if and when you manage to reach them.
SEM I tried on my practice project mini wing. Did several scratch tests and other fluids like AVGAS and break fluids on it. Decided against it.
I ended up with a 2K epoxy based primer used by airbus. It really is way to much work to set up and prep but the results are superb. So to sum up. I really wish I wasn't priming at all. It will slow you down tremendously.
My Process (takes a while):
Mix 2 parts (wait 30 min)
Then heat up booth to max temp possible for about an hour.
Parts are ready to withstand dimples and rivets the next day but it will develop chemical strength over time of a week or two.
Not sure if that helps at all. But pick your poison and move on to building. I spend months on this debate... I sure love the look of green "military" look on my parts... I guess I am a sucker for the classics.