I shoot an XD40 v-10, and I like it a lot. As for how the porting differs from other guns...
* Yes, you do get a lot more back-wash (and occasionally you can see visible exhaust from the ports). People observing nearby will definitely see a difference.
* My .40 is about as loud as a .357mag or .44mag, so I don't see why anyone would make a stink over it. I wouldn't recommend standing to either side with your mouth open, though

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* Front post does get very dirty. First time out, mine got blacked over completely after about 150 rounds. Fill up the divot with clear nail polish or neon paint, so that it's flush with the post. Then it just takes a thumb-wipe to clear it.
* Slide gets dirty on the last 1.5" or so.
* If you have a cleaning bench, or a toolbox, the mess can be taken care of by simply keeping a Ball jar full of solvent/lube (I go to about 3" in depth), and when you get back from the range, just field-strip the gun and put the slide and barrel nose-down in the jar. Next evening, everything wipes clean as a whistle, and the barrel just needs a little brushing by the chamber.
* Recoil on a .40 with porting is about the same as a 9mm - very nice for repeat-placement (and honestly this is really the only reason to get porting on a .40).
* Night-shooting, I couldn't tell you whether it's blinding or not. I suspect it would generate some unwanted effects, so if you plan to shoot a lot at night, don't get ported, or get a non-ported drop-in barrel.
* If this is a carry gun, don't shoot from the hip. You'll mess up your shirt, and if you're wearing wool, might set yourself on fire (not dangerously, but certainly humorously so).
Other than that, not much to say...it's definitely got extra "cool" factor going for it, and shoots as well or better than most I've seen.
Hope this helps -
T