Daytona 675's riding position is not as bad as a Ducati superbike. I am 6'0" and pretty comfortable so far for under 2 hours trips. I guess touring is not a problem for you since you have a Sprint for touring.
With Daytona, you'll learn to move your weight to the waist and peg your legs to the tank (sitting more forward).
GSX-R750 will be my choice for a sportbike supposed Daytona 675 didn't exist.
I think D675 will still look ageless in couple of years while GSXR doesn't. GSXR has a slipper clutch, though. It is also more powerful.
If you are broad shouldered like me (suit size 48), you'll find that the mirrors and windscreen are useless, too. But daytona is a very fun bike, you'll be like a 5 years getting his first bicycle

.