@ Nirvana
It is so easy to replace a sealed bottom bracket versus re-packing time vs money choose your poison. Brakes are better since the V Brake came out although disc brakes are making quit a push... big $.
I have a KHS Comp mtn bike and a Trek 520 touring bike both good solid bikes, nuthin too fancy.
Joe it sounds like your fitness translated to cycling pretty smoothly, most people struggle to get comfortable with those big miles.