I have great respect for those who adopt some personal code of conduct and fly by it. However you're only setting yourself up for disappointment if you expect others to agree with and abide by your code.
I don't see anything 'wrong' with flying off the map. If the tactic is well known and there is no clear concensus within the community as to it's validity, then using said tactic cannot justifiably called cheating. IMHO it's not even a true bug. You could argue it's an undesirable feature, but a true bug (again IMHO) is something the creators of the game do not know about and/or did not intend. The main arena is an unrealistic gamers playground and crafty gamers are going to do anything the game allows- be it bug or undesirable feature. To expect otherwise is as unrealistic as the arena itself.
From a strategic prospective I think off-map raids and HQ strikes in general are a poor choice. They are hardly foolproof, require expenditure of significant resources and take some planning to execute correctly. Even when successful, such raids only force an enemy, perhaps a previously disorganized one, to work become coordinated- usually to the direct detriment of the HQ strikers. Rarely have I seen any side suffer an HQ attack (sneak or otherwise) and afterwards have any serious setbacks unless they were already getting overwhelmed before the HQ hit.
I'll save my getting upset for where someone violates the rules of a scenario or when someone goes about breaking the spirit of a historical arena.
