Amped up rental markers

I like the idea of the cyclone but the 16" may be unnecessary.  You will get the same performance from a barrel between 8 and 16" but at the 16" point you start to get a little extra drag that can hinder the perofmance.  I would go with soething like a 12" J&J barrel.  They are inexpensive compared to many barrels but give amazing performance.  As for the RT that is up to you.  I am not a fan of the RT b/c of problems I have seen with friend's guns but if you take the time to tune them propely they will put down ropes of paint.  The expansion chamber isnt a bad idea if you do use the RT just because it will give the CO2 that extra time to expand and give better performance without the gun freezing up as quickly (I mean getting really cold not stopping) .  As for the Laser sight they are unnecesary.  If you do put a red dot on there it may make people think it looks cooler but unless they are properly dialed in they wont do anything.  If you meant a sight that actually puts down a laser on the target I highly recomend NOT doing it.  Could be a lawsuit waiting to happen if someone gets on in the eye.  All in all the 98 is a great platform gun to rent out.  They are tanks so you should be good.

edit* Spell Check

I would stay away from the RT just because of the danger of it failing and costing you money like oldpbnoob pointed out. Now new comers to the sport won't know much about paintball markers so they won't be able to see the obvious advantage to having a RT so they probably won't care whats in the marker, but they would care more for whats on it. What I would imagine is that a 12 or 14 inch barrel of some sort is a given, to insure better accuracy and then maybe a cyclone(emphasis on maybe) or just a cheap electro hopper like a VL or something. The customers might also view the laser sight as a advantage and be more willing to pay the extra to have the premium. I think you need to pack as much of the cheaper, yet higher functioning aesthetics as you can. I would stay away from using the RT, the expansion chamber, and the even the cyclone maybe just because of the cost to outfit your markers with these things. You never know how long it will be to pay off these things and you might want to start slow and see how much success and demand there is for the premium package and then maybe go from there to add a cyclone or the RT. 

hope that helps!