I do find it interesting to observe the split between people who think Glocks are unsafe because they don't have a traditional manual safety, and people who think that a manual safety is overcomplicated and therefore unsafe.
If you are used to drawing and disengaging the safety, it should never be an issue. I don't like autos with a 'positive' safety, because they add an additional motion to the firing process: moving your thumb back into firing position AFTER flicking the safety 'up'. When I fire my 1911, I rest my thumb on the safety, so the process isn't costing any time or coordination. I could go back to a Glock or an XD, but I don't see myself going back to a Beretta (mostly) because I despise the positive safety. (Although I had a T-92 with a regular safety that I had bad luck with as well.)
I don't see myself carrying with the safety off anytime soon. It took me a long time to get over the willies in condition one. I often use a fanny-pack, and once I opened it to fing the safety off. I couldn't remember if I forgot to engage it, or if my moving around had pushed it off. I now carry hammer-down with that rig. All my others, where I can see and check the safety anytime I need to I carry condition one. (In Utah, concealment isn't required.) Sure I could leave the safety off, doing so is merely stripping away one layer of safety. But on the other hand, why should you ever strip away a layer of safety? While you're at it, you could pin the thumb safety and cut off the trigger guard. Still safe, right?