You're going to see minimal recoil reduction with a brake on a 9mm blowback PCC. I put a brake on a 9mm JRC, which is one of the softest shooting 9mm PCCs we can buy, and I could barely tell that there was any reduction in recoil/muzzle movement. What it did do was significantly increase muzzle blast at the shooter, which I consider a negative for most situations. Waste of money IMO, unless you're a competitor that needs the extra muzzle blast to register shots with the timer, where 5% less recoil/muzzle movement could mean saving a tenth or two on the clock.
I took the brake off and put on a linear comp, which did slightly reduce muzzle blast when shooting at the CSC indoor range (compared to a FX9 with a regular flash hider). I noticed very little difference in muzzle blast between the two while shooting them at the outdoor range where the berms were far apart. So depending on where you shoot a linear comp may not be worth it.
You can't go wrong with a basic flash hider on a PCC IMO. Looks good, inexpensive, and they don't add much weight. The fake cans do help hide the ugly NR-length barrels if the forend is short, but they add weight and do affect balance. TNA does sell them with integrated linear comps or muzzle brakes if those features turn your crank.
My $0.05, having used them all on 9mm PCCs.