smoke'n it does not matter much what you carry so long as it goes bang. Also don't take what some gun shop sales person tells as the gospel ether. Most of them are like used car salemen!! They also have the same likes and dislikes for brands and no more knowledge than the average shooter.
I caught the same flack to with a M&P Sport.
If your holster works for you thats all that matters ain't it?? Just know that the right iwb can make a handgun the size of your xd's disappear AND work sitting or driveing.
Good luck with your holster design