FWIW, I have resprung my Adventure and it still bottoms chronically in the rear off-road. I had the forks working pretty good and they probably could be further improved with additional testing and adjusting. However, the shock is maxed out on compression and bottoms on everything. The bike has under 2500 miles on it. So since it probably needs a suspension service I am going to have to do the revalve. I'm a bit lighter at 195.
That said, springs may be all you need. It really depends how you are going to ride it. I would suggest respringing and if thats not enough, have it revalved.
Just my 2 cents worth.