I haven't yet but I plan on trying it. In the winter I usually go untucked. As a matter of fact, for personal style reasons I rarely tuck a shirt in when I'm not in a suit/office environment.
Also, no matter how good the IWB holster is due to the fact you've displaced so much waistline material in your pants it's fairly obvious you have something stuffed in there... that or you have one massive goiter.
That's at least the case with full-sized handguns. If I carried my Kahr it wouldn't be so obvious I suppose, but I never have felt 100% comfortable carrying a super small handgun daily.