I am looking to purchase a .45 1911 style pistol in the near future.  It will mostly be used for fun at the range, but I may also use it in IDPA matches.

Would adjustable sights on a gun used in IDPA-style competition be a problem?  How hard is it to find a holster that the adjustable sights will not catch on?

IDPA approved holsters leave plenty of room for adjustable sights.  I would strongly suggest you go with the adjustables.  I always need to use Kentucky windage with fixed sights.  That is no fun when you are shooting under a timer at tight targets.

Brian, I'm pretty sure adjustable sights are legal.  You can check at the IDPA website (www.idpa.com) and read the rules.  They mostly allow things that are stock.  So if you buy a 1911 that already has adjustable sights, you should be good.

Holsters aren't much of a problem either.  The IDPA website has a list of approved holsters.  (instead of just criteria, they actually have to be anal and approve every holster.)  Depending on what you get, you may have problems, but in most experience, adjustable sights don't have much problem with most holsters.  Try a few if you can and see what you like.  

This is My IPSC Limited / IDPA gun.

Page 9 IDPA rulebook, for STOCK pistol:

NO EXTERNAL MODIFICATIONS OTHER THAN CHANGING SIGHTS AND GRIPS WILL BE PERMITTED."

They do exclude

SIGHTS OF NON-STANDARD NOTCH AND POST TYPE.

Ghost rings?

Ghost ring rear sights are not legal in IDPA.

I shoot a 1911 with Bomar adjustable rear sight and I have no problems.  

Thanks guys.  I should have been more clear.  I know that the adjustable sights are IDPA-legal, but I wasn't sure if they were a good idea for IDPA-style shooting where everything is timed and having the sights snag on the holster or clothing would be a bad idea.

Bo-Mars will leave a real nice scratch on those with ample love handles. ( so I've heard, maybe seen once or twice)  But I have never seen them hang up on clothes or holsters.  You want to wear a tight shirt with a long tail anyway.
I'd say most IDPA and practically all IPSC limited, stock, & revolver shooters use adjustable sights.  Well worth the extra $.

Derek, is that a Hi-Viz front sight? How do you like it?  I have one on the way for my XD Tactical (and a black adjustable rear).  It seems as if the dot will be nice and large.