Like Rob2 alluded to, it's all about balance. The XDm 5.25 has a milled out slide because the weight of the slide might be too much for some very light loads that might be used in MINOR USPSA competition or something like that. I can assure you that with normal loads, even in 9mm, your Tactical model will cycle faster than you, or any other human, can press the trigger. If you are going for very light loads with reduced power recoil springs, you will also need to reduce the power of the striker spring as the slide recoil spring helps compress it and if it is too light the gun will not go into battery. So... if you have the gunsmithing skill and experience to start down this road, then ok, get the slide milled, but then the gun will NOT be usable in Production division in USPSA or in the several divisions of IDPA either. It will be only useful for Limited in USPSA or Open Division, for neither of which would it the best choice with the limited magazine capacity (Limited 10 maybe?) vs an XDm for instance. Range gun, ok. Competition... not so much unless something has changed in the rules that I missed.