It can get kind of confusing, there are several different types of XTP's close in weight to each other. Here are some of the ones you are talking about:

.452 250 grain XTP
http://www.hornady.com/store/45-Cal-.452-250-gr-HP-XTP/

.452 240 grain XTP mag
http://www.hornady.com/store/45-Cal-...40-gr-XTP-Mag/

.430 240 grain XTP
http://www.hornady.com/store/44-Cal-.430-240-gr-HP-XTP/

The .452 300 grain vs. 300 grain MAG are easy to tell apart - the MAG's have 2 cannelures and the regulars have 1.

I do not have any experience with the MAG versions, only the regular ones - specifically the .430 cal 240 grain XTP, and the .452 250 grainers. My 2 hunting buddies have used these bullets for the past 8 years at least and have taken dozens and dozens of deer with these 2 bullets. I can't say that I noticed a huge difference in terminal performance between these 2 bullets, it was fairly similar. They normally used 80 - 90 grains T7.

I do like the XTP's, and they do very well. For deer sized game they just plain get the job done. Now there are probably better bullets out there, but for the price they are hard to beat.

The Mag's are designed for higher velocities, but the non-mag's have worked well for us with moderate powder charges. If you want to use 110 - 120 grains of powder, then the mag versions might be an option...