I think this decision depends on your needs. If the FX3 doesn't have enough storage for the various sounds you want to use then perhaps an upgrade is warranted. If you don't have the volume you feel you need and don't want to bother with an auxilary speaker maybe another reason/excuse. Or, even if you feel you absolutely want the best unit available then go for it.
I can tell you from my experience with the Fury, I don't use anymore than 20 sounds but it is "nice" to know I have the capability to use the 100 it came with, not to mention the other sounds I purchased. I do all of my hunting just south of you and the volume is plenty given the terrain I'm in. The remote is cool, but it is sometimes cumbersome to remember and use all the features when you have coyotes coming in. The adrenaline takes over and I'm usually only focused on one thing. That's when I wish I had a large mute button only. But hay, if it's only money to you and you won't be happy unless you get a higher end model ...........break open the piggy bank and be happy. The FX3 IMHO is more than enough unit to satisfy 95% of all hunting situations the average joe is going to see in this sport. Stepping off of my soap box now. Good hunting to you!