I have some experience with the XDs. I have four of them, three 40s and one 45.
My 40s are the sub compact, the service model and the tactical, and the 45 is the compact model.
Of all the 40s, the sub compact is my favorite. It is very easy to conceal, especially with the 9 round mag in, but is not bad even with the 12 round mag in it. The 40 round is a little on the 'snappy' side and that has been mentioned many times here on THR as one of the detriments of the round. I personally don't have a problem with it, but if I was 75 I would try to rent one before I buy.
If your friend thinks he can conceal the 45 compact he might want to consider that one as well. It is not prone to the 'snappyness' of the 40 round and comes with 10 round and 13 round mags.
New XDs (not the XDM) in my neck of the woods go for around $420 to $450, but the sub compact may go for a bit more.
One more thought - the XD points more naturally for me than the Glock, just a personal preference. There are many accessories available for each now.