Don't throw any money at a problem until you know it exists. Put the adjustable Showas on and set the sag to the proper range. If you can't get both the static sag (weigth of bike w/o rider) and the loaded sag (rider with gear in riding position) within the desired ranges using the preload adjusters, then look to repsring. Don't ignore the static sag just to dial in loaded sag. I have used too much preload to get a good loaded sag only to discover that the static sag was almost nil and the suspension would top out too quickly when the bike got light over bumps or hill crests - not good.
There are two schools of thought on fork springs - some folks love progressive rate springs (most OEM springs) and some only run straight rate. There are pros and cons to each. Personally, after playing with about 3-4 spring combos, I have been happiest with a set of straight rate Ohlins springs in the adjustable Showas I have run on the Monster and on the SS track bike. I like the Ohlins better than RT because they are almost identical in dimensions to the OEM springs in length and diameter. (i'm funnny about little details, sometimes)
Unless you are running at or near Expert level race pace, Showa internals are good to go once you have the right springs/sag and maybe play with fork oil weight a little. One of the other staff members I ride with for STT picked up a Monster last season with no mods to anything and stock non-adjustable Showas, and on a very tight course (Talledega GP) was cutting laps faster on it than on his 99X SBK. But, he is close to the "average" weight that Ducatis are spring for from the factory. The only reason I've had to fool with my suspension at all isn't because I've found its limits through my skill, but because I'm a little heavy at 210-220 without gear and needed to get back into the proper sag range.
