I'm in the start-up process of an e-commerce site for predator hunting gear so I've been field testing the new FOXPRO callers for the last couple of months. My first FOXPRO was a Scorpion I bought to use specifically for bobcats. I then went to an FX5 and have recently used the Spitfire, Firestorm, Fury and Prairie Blaster models. They all work great but there's no free lunch either. More than anything, your budget will probably determine the caller you end up purchasing.
An occasional caller in "smaller" country would be served well with the Spitfire. Top volumn on the Spitfire (level 5) is about equivalent to the 24 setting (out of 40) on the Fury. The Prairie Blaster is a pretty specialized piece of equipment for big country or really windy conditions. But, it's a real pig to pack around. It uses eight D cells and it's pretty bulky. The PB does have a built-in decoy which is nice.
If you're more serious, the Firestorm and Fury will do most of what we predator hunters need. Between the Firestorm and Fury, the FoxBang feature on the Firestorm is pretty cool but overall the remote for the Fury is much nicer to use in the field. It's quicker to find/change sounds. It has more presets. And, the buttons are somewhat easier to operate especially with gloves on. The Firestorm has just two presets and one of those is used for your FoxBang feature. If you start with the Firestorm, you will probably get used to it and get along fine. I made the mistake of using the Fury first! Sound quality with both callers is similar.
Again, there's no free lunch so choose the caller that fits your hunting style and budget. I can tell you from first hand experience that they all work and you can kill coyotes over any of them! Fell free to PM me if you have any additional questions.
Tim