Fortunately I don't have the hip problem that you described, so I'm not in that specific circumstance. But I am turning 50 next month and wanted to treat myself to what I assume will be my last bike (meaning it will last a long time), so I bought a Vamoots earlier this year. I got a stock 58 with the taller 18cm head tube (no charge for that by the way), the Vamoots fork and the matching seat post. I don't have any flexibility problems at all, but I like an upright ride so I went with the taller head tube. It took 9 weeks to build, but it was worth the wait. The bike looks fantastic and rides even better. To get even more comfort, I went with custom wheels of HED Belgium C2 23mm rims laced 32/28 3x to Velocity Race hubs and the ride is super smooth, yet very quick and responsive and it track straight as an arrow. I was coming from a 1993 Serotta Colorado tg which was no slouch in the comfort department, but the Vamoots beats it in every way. The only dilemma that you have that I didn't is that I think the Vamoots is their BEST looking bike. I love the classic look of the less sloping top tube and I like less seat post showing, so I actually got what would be my first choice from a looks point of view. By the way, by going with the extra 1cm tall head tube, I ended up with a little more top tube slope than the stock 58. It's very little, but that's one way to get a slight bit more slope if you like that look. And, yes, I got a pump peg! Wouldn't want a bike without one.
Anyway, go for it! You'll be glad you did.