The most important thing I picked up is that they get really dirty really fast which caused jams after about 75 rounds of sustained fire. Prior to the magic 75 round line it functioned flawlessly. That being said, my XD has at least 2500 rounds through it and has never been cleaned. Its only failure to fire was from a casing that actually bent on its way up the feed ramp around round 800. It's an ongoing experiment and it isn't a concealed carry weapon or primary home defense weapon. I'd also go with an XD because of the rigid spring guide. It helps keep the weapon from going out of battery when pressed directly against a target, which is a problem with most automatics and a valid concern for a concealed carry gun.
Additionally, someone asked about fiber optic sights... I have a set of Tru-Glo tritium fiber optic sights on the XD as well. They're splendid. I tried to run them out by putting the XD in a desk for a couple months. Whether it was from the tritium or because of the light gathering properties of the fiber optics I couldn't say, but even with nearly total darkness after two months in a desk drawer with no lights, no windows and the door closed there were still three unmistakably bright little dots. I actually wonder if they'll mess with my night vision.
As for your confusion...tritium remains bright due to radioactive decay (without the need for ambient light), but fiber optic polymers gather ambient light and focus it in the linear plane of the fiber (i.e. end to end).
I really don't understand why you'd have both tritium and fiber optics, unless you were trying to save money but not having tritium front and rear.
Tru Glo tritium fiber optic sights are great in my experience. A lot of SIGs come stock with them. There's tritium inside the fiber optic so it glows a bright green in any lighting.
so what, the phospor material/trapped tritium gas is physically against the fibre optic material? never seen a tritium sight, by way...
I'm not entirely sure how it works. Its out there though and its a good product.