Sounds like a fun project. I ended up getting a used Long Haul Trucker frame and moving over the best components from the RockHopper build I showed in post 19 above, so a lot like what you suggest you might do with the Saga (except the components I started out with weren't as nice as what you're getting. Earlier tonight I finished rebuilding the RockHopper as a beater MTB with 9-speed components. I used the original wheels but replaced the old 7-speed freehub (not freewheel) with a freehub from a Tiagra hub I wasn't using.
Tinkering has been half the fun with this bike. I think I've ridden it about 800 miles and rebuilt it five times in different ways.