Got a G21, G20, and G29 in addition to other calibre Glocks, but not a G30. The G29 is identical in size. They hide well with the right rig, I like a Milt Sparks VMII. I have a VMII for my G27, and I'd have to say they hide about the same.
The G21, which has similar feed ramps, etc., will eat just about anything you can put down it, anything jacketed anyway. 200gr. +P Gold Dots work great, those in the G21 are my weapon of choice for bedside. If for some reason those are a problem, the Hornady XTP's feed almost as well as FMJ.
You can change the recoil assy., but it isn't really necessary. I have a bunch of different recoil assy. and the ones I use for carry are almost always either stock or titanium with a stock sleeve and stock spring. The fancy ones and steel ones are for target use where I have to change spring weights more often. Using aftermarket springs can affect reliability with factory full power loads --heavy recoil reducing springs can cause failure to cycle or stovepipes.
The one thing I would consider changing are the sights. Stock Glock sights suck, but I am glad they come with them to keep the cost down so I can choose my own. I like the Trijicon for carry and the Meprolight adj. for target work.
Other than being ugly as sin, I can't think of any problem with the Glock pistols. I've been using them since the mid late 90's, the G21 is 15 yo with zero problems. Thousands of rounds, and I can't think of a single problem with that pistol using stock parts and full power ammo.
When you start running into trouble with Glocks is when you start fiddling with the parts, aftermarket stuff, and handloads. I load weak 9mm loads for target use, the G17 will jam now and again and sometimes not cycle at all unless I use a 13 or 15lb. spring. I have had more problems with aftermarket barrels and slides than anything else.