Stookey - Tyco's system is a dry system and I is good for Class II or III commodities depending upon building height. Usually takes a pretty hefty fire pump.
Viking's antifreeze system is still pretty pricey and makes for a big maintenance headache.
My guess is you are trying to stay away from in-racks so I would look strongly at the Tyco Quell system first.
it depends... the quell system usually requires a large fire pump so if you have a small warehouse (for example 20,000 sq. ft.) it would be more cost effective to install in-rack sprinklers if the city water pressure is adequate.
If you have larger warehouse or need a fire pump regardless the quell system will be more cost effective.
Also, their are the maintenance costs if you eliminate the in-rack sprinklers since those never get hit by forklifts.
Contactors need to be licensed by Tyco to install the Quell system so not every sprinkler contractor is qualified.
One thing to be very watchful, make sure with your system that you have adequite protection around your cooling units. If you have a rooftop "penthouse" be especially careful with your installation because your insurance company will go nuts if heads aren't set up right. Even with a contractor who was licensed by the designer, my facility ran into all kinds of trouble.