So is it a balance issue or not? I'm less concerned with "realism" - Trailblazer should be proof of that.
Serious question: What part of Trailblazer should lead me to conclude that a 40% acceleration resulting from simply turning 45 degrees is not within your "realism" threshold?
I know it sounds snarky, and I apologize if it comes off as nothing less, but I really mean the question.
In a related manner what other properties applicable to commoners and puppies does Trailblazer disregard because no reason other than "realism" applies? Is there a reason other than realism for why commoners can't all walk up walls?
To me RPGs are much more than tactical games and getting it right is important. At least when it is really easy to do. And 1-2-1-2 is really easy to do.
1-1-1-1 has tactical implications, but it comes a long way from "breaking" the game. Balance in not on my radar when I think about diagonal moves.
But when I see 1-1-1-1 it immediately tells me that either the game does not expect to live up to a high standard of being right, or it just doesn't think very highly of the capabilities of its target audience.
In my games things that are not realistic fall into one of two categories.
1) Features of the game.
2) Failures of the system.
And BOTH do exist. Accepting and mitigating the second kind is part of the process. Hit points are the obvious prime offender, but there are certainly others. But any time an easy fix for a failure exists, that fix should be implemented immediately. And 1-1-1-1 has an amazingly easy fix.