First I'll preface by saying that I've shot every single Glock that's been manufactured. Yes, even the G18 WITH a shoulder stock.
With that said, I think the compensator does do a decent job of reducing muzzle flip, which is already not any big deal in the 9mm G19. It's just a ***** to clean. You'll have a lot more copper and powder fouling on the top of your gun and in the ports, which will require more scrubbing to get off.
Personally, if you're looking to carry concealed, you may want to consider a G26, since its a bit more compact. But if you're looking to hit the range a lot, the 19 is better.
My two carry guns are a S&W 342PD in 38special and a Glock 36 in 45acp. I carry the S&W while I'm in a suit going to and from work and I carry the G36 mostly in the cooler months, where the larger gun is more concealable. The G36 can be tough to conceal if you're wearing a t shirt, which may draw attention to you. The G36 is also smaller than the 19 you're looking at by a little bit.
Now with your ammo choices...what are you thinking?!?!? You DO NOT want to carry a mixed load EVER. You actually want to put wad cutters, hollow points and full metal jackets in the samg magazine? Dude!
Stick with the load I use in my G19, the Speer Gold Dot 124grain +P load. Load the WHOLE mag up with it and if someone tries to rob you, you'll brighten their world one bullet at a time. You should also carry WITH a round chambered, as in a shoot or die situation, you WILL NOT have time to rack the slide and engaged your targets effectively. You can drill yourself all you want, but the safest way (so you live) to carry is with a loaded chamber. If you don't have the discipline to carry with one in the tube, you probably aren't comfortable enough with a pistol yet and you should not carry.
PS. You may want to think of a 5 shot J frame S&W like I have. I carry in a pocket holster and can have my hand discretely in my pocket holding the gun in my hand without having the need to draw it if there were unsavory characters around.
Good luck in your purchase!