I have one in .45 and one in .54. If weight is a factor that concerns you for color guard use, the .54 will be somewhat lighter. However, for target shooting you will spend less on lead balls and powder over time using the .45. Also, some folks prefer a heavier barrel for target shooting, which the .45 would be although not by any large amount (you would need to check with Kibler to get the actual overall weights). The .45 will have a bit less recoil as well, but again, we aren’t talking huge differences there either. I haven’t noticed either caliber to hold any advantage over the other in terms of accuracy.
Jay