On the .45s, the XDMs have a recontoured grip with replaceable backstraps. The original XD45 is just a pinch too big for me.
If you want a full metal high(er) capacity .45, see if the Megastar is on Cali's list.
I've used Gunbroker lots, maybe 75% of my current inventory is from Gunbroker. Only two negative experiences. One, a pistol where the mag would stick after firing and the guy shipped another mag...which wouldn't take full capacity. The other one, I paid for 1,000 rounds of 7.62x51 brass and dude shipped me 5.56x45. Said he was shipping out the return label that day, I got busy, it never came and the jackwad is no longer on Gunbroker.
Check the sellers feedback. If they have crap negative feedback, don't buy from them.