Low bench all day. The whole back pain thing gets overblown. A good stool and taking breaks fixes that. You just can't beat being right on top of delicate work. Most of the best shops I've seen run lower benches for a reason.
But what kind of work are you doing most? If you're building wheels or bleeding brakes all day, that low bench is a killer. If it's just occasional cable housing cuts, maybe you can tough it out. Your back will tell you what's wrong before your fingers do.