Time flies doesn't it??? You've done your job well ... so your option is what is best for my dog?? You got it right so "Job Well Done."
That said ... since I "unintentionally" Proofed the concept of "Neutering" will fix issues, I'll share my observations with that as a solution. LOL and most likely ... you know where this is heading?? And my answer, observation and experience is uh ... "NO," it won't!
Neutering to fix "Behavioural Issues" is usually the first resort of the desperate??? And typically it makes ... no difference??? We don't really see a lot of "Bad Dog" Boxers on here ?? Dogs with serious "I'm gonna hurt somebody or cause injury to my owner because I am such a tool dogs on here??? But on GermanshepardForum, we did!
Day after Day ... Week after Week, they rolled in all the time! It never ended and usually, getting them "Fixed" would be suggested ... LOL yeah ... "Good Luck" with that ... I would say.
AFAIK, the biggest PIA Dominate Male Dog, I was aware of in my neighborhood was uh mine??? He was a foster fail that I got at 7 months and he was already "Fixed" when I got him. And being "Fixed" did not mean "Crap to him???"
Most likely he was fixed at 6 months?? So myth one dispelled ... stunted growth??? At 116 lbs, 8 months later or so he was ... way oversize ... so that did not happen (stunted growth) ??? And then we had the Pack fights with my other Dominate Neutered males (and my trip to the ER breaking up one of those fights) and the out right hostility to uh "everyone" aside from me and my wife ... he was not a fan of people!
In theory ... since he was "fixed" he should have been "No big deal??" And a "Wobble Dog" on top of everything else ... so "he should have been safe enough??? Clearly such was not the case??? Oh well it worked out well in the long run! Most likely, I put to much faith "unknowingly" in the "neutering thing" so I was kinda slow to see issues developing??"
And ironically enough and although I did not do the other dog thing ... he got along great with unknown dogs??? Enough so that I understand why a lot of trainers use GSD's and Mal's in there rehab work with aggressive dogs! I've not seen anyone I follow use a Boxer in that work??? Personally I feel ... that if a Mal, can do that work then so can a Boxer??? Both are kinda pigged head and stubborn but I have never had a Mal ... so I don't know???
At any rate it's your call as to "fixed" or not??? I think I'd vote no myself? Now if you decide later on to add a girl ... Boxer or GSD, that might be a different issue???