I understand what you say and you explain it better than I can, but, in my experience, I have never hit the 900 'flying hours' limit without being credit hours limited first. The question has always been whether the lifestyle balance can be achieved within BA.
As you say those hitting 900 hours have been choosing to do overtime. Careful bidding will see you hitting your credit hours limit well before you hit the flying hours limit which is more comparible to the VS position. Most importantly the way you bid, the hours you achieve and the destinations you go to are yours to choose when you have the seniority in either seat.
Sorry I didn't make that clearer.