These are my 1st & 2nd shots from my Gaggia Coffee that arrived today. Why they quit making this unit is beyond me - it is heavy built, looks great, and is easy to operate. I think the Virtuoso mates up OK if you want OK espresso - these shots were not exactly swill - but I consider it to be the weak link right now in my quest for mastery of espresso.
For Variable #1, I think a decent espresso grinder will create the proper resistance to make the pressure issue a non-issue. Since my budget is limited (next expenditure will be a nice grinder), I am going to try to master the elusive temp surf for variable #2 but will consider purchasing a PID if I am not successful.
I'm impressed that you got that far just out of the gate!
It's my opinion that the new owners of Gaggia saw the old Espresso/Coffee/Carezza/Evolution line up as being essentially the same machine, which they were internally. The Evo is the prettiest of the group and being plastic, cheap to make. Thus, the rest were redundant. Like you, I believe the Coffee is the best of that group.
V1 isn't resolvable by simply grinding finer. The idea is to properly adjust the pressure and then dial in the grinder. It's akin to making a car go faster; do you just dump more gas down the cylinders or do you tune the motor to make better use of the fuel it really needs?
If you check with the members over at the Gaggia forum, those who've modded their machines with an adjustable OPV will tell you it's one of two must-do mods to get the most from your Gaggia Coffee (the other is the SPV fix). The 1st mod costs ~$50 and the second ~$3, and you'll see an immediate improvement in your coffee!
Good luck!