Hi,
I can't speak to an XDM, but I'm working up loads for a Glock 34 (noted for finicky cycling) and titegroup. I spent hours on this and several sites, and constructed a spread sheet of various folks loads using titegroup and N320 with various bullets. Like you I found little documentation of Xtreme. In one of the threads someone asserted that RMR was actually a re-seller of Xtreme, so I logged RMR and Xtreme data as the same.
DISCLAIMER: I am a VERY NEW hand loader.
I can't chrony in my indoor range, so for now, I'm going by accuracy, primer inspection and feel when I shoot.
First range outing:
3.2g TG over 147 Xtreme plated 1.15 OAL 10 rounds
3.3g TG over 147 Xtreme plated 1.15 OAL 10 rounds
These shot almost identical, with one possible tumble on the 3.3g. Primer's looked perfect. . . Based on this, I figured there was no sense going to 3.3.
Second range outing I shot 50 rounds of the 3.2g recipe above. Nothing wrong, but I wasn't really happy with the grouping. I'm not an excellent shot, but I seemed to shoot the 124gr Aquila factory stuff better (maybe my gun just likes 124 gr????).
Third range outing:
10 rounds 3.2gr TG over 147 Xtreme 1.16 OAL.
I loosened my Lee factory crimp die to 2/3's turn (instead of half), and increased my OAL to 1.16. This tightened up my group by 1/3-1/2 of what it was. Very happy with the improvement.
I'm trying to think through what my next step might be. Make up 50-100 and shoot away? Go to 1.165 OAL?...
With regards to the Lee Pro Auto Disk. Get the adjustable charge bar (http://www.amazon.com/Lee-Precision-Adjustable-Charge-Bar/dp/B00162RPDG/ref=sr_1_1?ie=UTF8&qid=1383799360&sr=8-1&keywords=lee+charge+bar). Before using it, get some cold weld stuff and fill in the end of the cavity. As distributed the charge bar doesn't throw small loads certain powders (3.2gr of TG) well. By filling in 3/16-1/4 of the cavity at the end, you move the cavity back so that it centers under the powder disk better, and get a better drop. Search this and other forum's and you find documentation on this and pictures. Most use paper, I just find the cold weld a more permanent adjustment. It will totally throw off any documented dial adjustments, and any charts that Lee has. After you do that, you'll need to adjust and weigh until you know what dial position throws what powder load. I can throw very consistent loads of 3.2gr with generally a .05 or less tolerance and the occasional .1 tolerance This means 90+ percent of my loads are 3.2gr, 8-9% are 3.2gr +- .05 and 1-2% are 3.2gr+- .1gr. I can live with that. (remember my disclaimer above).
I'm also going through the same exercise with 124gr FMJ's (Winchester I think), on the theory that my gun likes 124gr.