The individual model scale, combined with the Zone of Control concept, is probably my favorite aspects of SBG. This is also it's biggest problem because, as mentioned, it can create very long turns. Most of our local team could take several minutes to move their side in the later points of a game where you're trying to decide who will charge where while blocking other model moves and calculating combat odds, planing Heroics, anticipating your opponent's reactions and moves and then projecting all of this out for next turn as well, accounting for each possibility based on who wins Priority.
That's the nice thing about playing in a hobby shop. You can go off and browse the shelves, talk to other players, make a purchase, use the bathroom, get another drink and then return to the table to do it all again for your turn.
The problem you describe, as others have mentioned, is far more of a player attiude issue than anything to do with the system. I've seen movement trays in WotR shift and have issues due to hills or other non-difficult terrain. You have to remember it's just a game. Don't try to cheat but don't get hung up on a 1/4 inch difference. If there's a disagreement, dice it off and move on. If someone has that much of a problem don't play them again. As hinted at above (only partly in jest) our local players are comfortable enough with each other that we may even step away from the table while the other is moving. If a die has to be cast then someone is called over to watch, but we don't get hung up on the move/charge too much. We are all honest players and it's far more important to all of us to have a fun, fair game that we all feel good about at the end than it would be to try to sneak an extra 1" move on Aragorn just to have a chance of winning.
If the players are friends or at least respect each other and everyone has personal integrity then such issues as falling or shifting models should really be a non-issue.