Just wanted to share my experience with the PRP drop-in trigger kit for the XDM's. This works on all XDM models. The stated pull-weight before the kit is 6-8 lbs. After the install reportedly around 3.5-4.5 lbs. I do not have a measuring tool to test myself but I can say that there is definitely a noticeable and overall difference. It's also designed to have an SRT-like benefit as well.
The install took about 20-30 minutes if you take care and the time to make sure it's done right. There are several steps that are absolutely critical for a proper install. I would recommend the PRP video as found on youtube (links available on their website). I did not opt for the match kit as there is often some minor fitting required either with some sandpaper or a file.
I would say that the kit is very nice, but a bit pricey at around 125 bucks direct from PRP. I believe it was a worthwhile purchase and plan to install it on my 5.25" 45ACP XDM as well.
-C