Well even though you've already ordered the 98 you made the right choice. I have a Spyder Java with mini expansion chamber, modified bolt, trigger job and Dye grips...not major upgrades but the gun isn't completely stock.
My friend has a Model 98 for about as long as I've had my Spyder. The Tippman's are really tough guns. Everytime we play I always have to tear apart my Spyder to clean and lube it or else the next time I play I'll be breaking balls left and right and the gun will jam and it's just a big mess. My friend hasn't opened up his Tippman since he bought it and it still shoots like a champ, no problems whatsoever...altough replacement parts for Tippmans are expensive.
Looking back on it I should've gone with a 98 but oh well...good luck with your purchase and enjoy!