The Tippmann 98 has actually been around longer than the Inferno Mk2 which has been in production for under 3 years, i believe. The only part that generally needs replacing on the Inferno is the valve, which is under a fiver, and occasionally the valve guide. Most other parts last for years, even with the abuse our customers throw at them. Have you actually studied the machining and tolerances on Inferno parts? I doubt it- they're flawless.
We have found the Inferno to be more reliable than the Tippmann provided it's is kept clean and oiled, which is part of a good marshal/managers duties. IMO, the only benefit a Tipmann has over an Inferno is the ability to fire when full of mud, grit and paint. But that's not good for the long-term life of the gun, so really you gain nothing.
Problems we encountered with the Tippmann were LOTS of valve problems, and the 98 valves are a biatch to service. They are not designed to be end-user servicable which means you either hold a lot of spares or you have a lot of down-time. Power tubes cracking were another problem we encountered and sears made from cheese, well it seemed that way..!
End of day maintenance on a Tippmann may be easier as some sites just hose them down or use a pressure washer, although Tippmann don't recommend this. However, if your marshals are trained properly it takes just seconds to remove the bolt from an Inferno, squeegie through, oil the hammer and replace the bolt and give the gun a quick wipe over, which is all it needs.
If we're takling about stripping a gun down to fix it then the Inferno wins hands down, and yes i've worked on both as site guns.
I think you contradict yourself there, Sputnik. If Tippmanns last as long as you suggest then a site would have to buy new guns less often so their fleet of guns would be very old
I think a customer would put the make of gun pretty low on their list of priorities when choosing a paintball site. Usually the top 4 priorities when picking a site are: 1. Cost/value, 2. Location of site to where they live/ transport links, 3. Site facilities/scenarios and 4. Word of mouth recommendations.