Well first off, you should've considered the pros and cons BEFORE you spent your money!!
But I do stuff like that too, so don't feel bad.
I will difer with your comment that it is "only" 9mm. There is absolutely nothing wrong with 9mm as a defensive caliber. Some loads are better than others when it comes to penetration and expansion, etc. But I differ with many people's "opinion" that the 9mm is underpowered. It depends on WHICH 9mm!!
Sure, I prefer a .45ACP. It's what I came up on and the 1911's feel great in my hand...but most days I carry a little .38 snubby loaded with standard pressure .38cal 125gr. nyclad hollow points. Sure, not your BEST in penetration or expansion, but I beleive that even if you are shooting a .50 cal BMG, it only works if you can hit what you aim at. I also recently purchased a G19 for the wife. She LOVES it! Can't shoot worth a darn yet, but we're working on it!
Anyway...the only problem that I would see with your choice was that your backup/off-duty weap is in a different caliber than your primary.
If you work in plain clothes (as I do), you might consider either the G23 or the G27. These are lighter and easier to wear and they use the same ammo as your duty weapon.
You may be able to trade that 26 in towards the purchase of a 27 in .40cal...or maybe you could go to a G17 for duty use? Either way....if I am going Glock for both duty and backup/OD then I am going to get the same caliber for both. (Or I may use a revolver for my backup, actually)
Those are the pros and cons as I see 'em...
As far as holsters...this is a very personal choice. The pursuit of the "perfect" holster is alot like the pursuit of the perfect jacket. You keep looking until you find something better than the one you had before. In the end, you have a couple of favorites, and a cardboard box full of holsters in the closet.
I like the new fobus holsters for those baby glocks, but I haven't actually worn one. They look pretty sweet though! As a rule, I tend to like a good leather pancake holster, or I often use a paddle holster for easy on and off and storage in the desk drawer once I get to the office. If I had to choose just one, it would be a good pancake!
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Sparky