I owned a '97 XX (carbureted) and own a '03 XX now. For a few months, I had the two at the same time.
The carbureted Birds get slightly better gas mileage (and the fuel tank is about 0.3 gal. smaller, as well). The OEM pipes match different cylinders between the Carb and FI models, but most aftermarket pipes use the same pairing of downtubes as was on the Carb'd Bird (or maybe the FI -- can't remember??) for both FI and Carb Birds. If there's a difference in perception of power, it's probably there -- something about mid range vs. top end power that was the point for Honda when they changed that with the FI introduction.
I like FI primarily because I tend to ride widely varying elevations in a single ride. The FI compensates better, while the carbed bird jetted for 1200 feet is running rich above 6000 feet. But the carbed bird handles it well enough -- not at all like it lags or is gutless, even at 9000 feet. FI is a lot easier to change mixtures (like when adding an aftermarket pipe) via a simple map change in a Power Commander than getting into 4 carbs under the tank to install a jet kit.
The 2000 and later (or maybe 2001 and later) has the best instrument cluster setup of any bike I've been on. You get the all analog, somewhat small numbers, but adequate cluster setup with that '98.
Buy the thing if it's a good price. It'll probably go 200K miles -- well built and nearly bulletproof. The earlier birds tended to go through R/Rs (at least if it's ridden mostly short hops where it's getting a workout and heat loading -- poorly finned for heat dissipation), and the common fix was to wire one from a Yamaha R1 in its place. Cam chain tensioners are another easy fix of something that tends to go out making some noise sooner or later. Other than that, make sure the rubber is good and you've got a great bike, probably for short $$.
