In my experience the 26 is only slightly more concealable than the 19 (I carried a 27 for about 2.5 years before switching to the 19). If it were a little thinner, allowing for pocket or ankle carry, I might feel differently. But if I'm going to have to wear it on my belt anyway I prefer to have a duty size weapon which the mid size Glocks just barely make that category in my opinion.
I have a Glock 26 that stays under the dash and I carry a Bodyguard 380. I keep a G17 mag in it with a slip-over sleeve making it very comfortable in my hand. If my clothing permits me to carry this, I switch to my G26 with a 10 round mag. G26 is pretty easy to conceal and you can use higher capacity mags with no loss in reliability. It gives you options with no loss in function and reliability. My only comment is to by good mag sleeves and do not over tighten the sleeve on the mag.
BTW - I'm selling my trigger guard laser (Crimson Trace - $125) and the guide rod laser (LaserMax $150) for the G26 if you buy one and interested.