I assume you're talking about the G5 squaring tool. Yeh, it's expensive, but, sorry to say, the only one on the market presently.

As to whether the arrow not being cut square is bad? I've always wondered about this myself. The insert fits pretty snug in the shaft so just how much can it wiggle, really? And I do as you do for checking broadhead alignment. Put the broadhead on the insert and then glue it in the shaft. Adjust for alignment before the glue sets up. That's why I'm a firm believer of 2 part epoxy. And just possibly that little bit of glue you wipe off fills in that slight void from an imperfect cut. Just my thougts on this.

I will say another thing about alignment. I use an InnerLoc head, which is similar to the Muzzy. The blades slide into the ferrule from the front. Once I have a ferrule on a shaft I never take it off. That's where it stays till I change arrows or broadheads, which isn't often for hunting.. I can still practice with the arrow, but put new blades in for hunting witout messsing up the integrity of the alignment.

This something that a lot of guys don't think about. They will build arrows and align everything practice with them and everything is fine. But when you take the heads off to change blades they don't always seat exactly the same every time when reinstalled. And for those that don't know, the head must go back on the exact arrow that it was removed from.