I've steered away from Glocks because of the lack of externally mounted manual safeties.
I grew up on 1911s, and now swear by the XD line.
I toyed around with the idea of getting a Glock for my bedside gun in either .40 or .45 until I shot a couple of them. The lack of external safety doesn't matter to me in the least bit. As a matter of fact, the Glock does have an external safety. The safe action trigger. One of the same safety devices that an XDm has. What did matter to me is I tried a test that a friend of mine led me to one day.
This post might get a little long as I describe the test and what the results meant to me, so if you aren't really interested in the results or my decision to not buy a Glock based on the results, just know that I didn't buy it due to the grip angle.
That is the short version, here is the long descriptive version.
This was back in about 2001 or thereabouts, so whatever generation of the Glock that was out then is the one that I was shooting. At the time of this test, I was using my S&W 5906 9mm as my primary pistol and was wanting either a .357 Sig or .40 S&W (was leaning towards a Sig P229, but was also open to the idea of other pistols) when a friend of mine offered to let me shoot his G23 to see what I thought about it. As soon as I picked it up, it felt odd in my hand, but then again, so did the H&K USP Compact that I had shot about a week before that so I (wrongly) assumed that it was just because it was a polymer framed pistol and I wasn't accustomed to it. Since I wasn't closed off to the idea of a polymer gun (mainly because by this point, Glock had already proven themselves to one of the, if not the, most reliable handguns ever built) I figured I would give it a try and see if I could overcome the odd feeling via training. Thought that maybe if I shot it enough, it would eventually feel comfortable. After 3 or 4 magazines, I noticed that my wrist was hurting a little bit and the palm of my hand was starting to get a little sore. I mentioned this to my friend and he told me to try something. This is the test that I had mentioned. He told me to line up on the target with the Glock in my hand, but at the low ready. After this, he told me to close my eyes, and while they were closed to aim at the target. I though this was funny, but considering at the time, I was about 18 or 19 and had not shot a whole lot, and the guy that I was shooting with had been shooting longer than I had been alive, I complied and proceeded with the test. I tried my best to remember how close to eye level the target was (which although I ended up pretty close, this turned out to not matter as much as I thought it was going to at this point in the test) and raised the pistol up and did my best to aim center mass. After I got settled, I opened my eyes and realized that I was looking at the top of the slide. Although my hands were pretty close to where they needed to be, the pistol was actually pointing above the target. I was about 10-15 yards away from the target, and if I would've shot, I would've missed the target. Now granted, you never shoot with your eyes closed, but the point is, where my body naturally wanted to aim did not match up to the frame of the Glock. I had heard that the grip angle on a Glock is more extreme than most pistols, but I had never really put much thought into it until this test. After this test, I thought about, what if someone kicks in my front door at 3am. If I wake up, grab my pistol, point (in the dark) towards whoever just kicked my door in, am I going to have positive aim on him when lighting is less than perfect? Granted, night sights would fix this, especially if the front post sight glowed a different color than the rear sights, and practice would probably overcome this issue, but why should I have to train to overcome a particular feature/flaw/design of a weapon (unless it was my issued weapon, in which case you train because you have no choice). In civilian life, I have a choice and that is why I chose not to get the Glock. That being said, I just bought a XDm the other day, and before I bought it, I rented one and fired the hell out of it just to make sure that it was exactly what I wanted. I had thought about the possibilities of certain issues with the grip safety, but had decided that it wasn't enough of an issue to steer me away from it. Once again, if there was an XDm offered without the grip safety, I would've bought it instead, but as it stands, I bought the one I did. If in the future, I decide that it is more of an issue than I do right now, I will look into ways of disabling it so that it will not be a factor. Which kindof brings me back to what I said before about it. Is it needed? No, I don't think it is.
One more thing, I have not shot a Gen 4 Glock, but I have been told that if you use the small backstrap, it reduces the grip angle to a more natural angle. That being said, I might give Glocks another look as a bedside gun. When I decide that I want another gun, the 5906 will move into the center console of the Jeep, and a larger caliber handgun will replace it in the nightstand. Most likely another .40, but I will also look at .357 Sig and .45 when I am deciding. Or, when my 870 gets delivered, I might go ahead and put the 5906 in the console, and just keep my XDm near enough to the bed, along with the 870. With a 12 gauge laying there, I doubt I would reach for the handgun anyway.
Sorry about the length of the post, but hopefully if you weren't really all that interested in it, you didn't read the long version and if you did read the long version, hopefully it helped in some way.