I work at a popular gun store here in AZ. I carry a XDM 9mm when working at the store.
XDM's in 9 and 40 as it's all they make. We have several models those (bi tone, green, tan, black) and seem that someone always wants the one that's not there. Thus the joy of ordering. However the all Black 9mm and 40's sell the best. When the XDM came out our sales of the standard XD's dropped off considerably. EXCEPT in the sub compacts and the 45's. Like Desert Ram pointed out, ANYTHING SUB COMPACT is in high demand right now. That's evident by the amount of CCW's being pushed through each and every state.
The XD 45 sub compact and 4" model as mentioned above are real big sellers and hard to keep in stock.
We usually keep 15-20 XDM/XD's in stock at all times and dont have a problem moving them. Another note, because of the different grip sizes available on the XDM many men with smaller hands and women have a great deal of interest in them. Glocks (even the SF line's) have a large grip to say the least. A big line we preach in our store is "if it feels good in your hand, it will probably feel good to shoot". Not many people can say that about the glocks.
If you have a competent gunsmith in your area you can really increase the sales of them too because people always want the work done to them that mine have. I sell allot of XD's when I'm working because they feel the trigger on mine, see the suppressor on my 4" 45 and want to know where they can get it done.
I'm a huge glock fan (like many) and own several of them, yet I carry the XDM in the store because of the 20rnd capacity. I also started carrying to help with their sales. No other employee at my shop owned or carried an XD product as they are mostly glock, sig or hk fans. All good guns but I wanted to be able to speak on the XD's as well.
From a personal stand point, being a glock shooter for several years I was use to the feel and the trigger. I can shoot glocks very fast and very accurately after modification to the triggers. This was my complaint about XD's and XDM's.
After talking with Rob Latham at Usery Pass one morning he told me the that Derrick (Accuracy Speaks Gunsmith located at the range) did wonderful work on the triggers. I headed over and dropped mine off. Now I can shoot it like a glock which for me is a big compliment considering the years I have shot those.
Sorry to be so long winded, especially with information your probably already know.
Good luck with your sales