Agree with @artemus that there might be small differences
define "small".. ..are you speaking from experience or from what you’ve read?
seems to me if the goal is to be the best that it can be then you are potentially leaving something behind if you "settle" for the shorter arm. As I started down the path of higher end arms - tables - cartridges I found that there were huge differences as you get into the upper levels and you are well rewarded for taking the time to precisely align it all. Feel free to come back at me with... define "huge" :)
I agree if you don’t want to invest in the proper tools and spend the time to optimize the setup then stick with the easier path, but if your are "going for it" then go for it with the longer arm. Of course, I will be comparing a shorter Morch with a longer Kuzma so nothing definitive will come of that in regard to whether longer is better (or worse) or if it is Morch vs. Kuzma.