As Dave suggested the 17 Reminton has been available for years both from TC and custom barrel makers for Contenders, the 17M4 from custom makers for years and from TC's so called custom shop not as long. Imagine some of the custom barrel makers are already set up to do the 17 Rem Fireball.
Those who don't reload will go for the 17 Remington Fireball, but those of us who do reload and have had 17M4's for years will probably never buy one. I know I won't.
Dave makes a good point on versatility, but I've never felt like I gave much (if anything) away carrying my 17M4's instead of my 17 Remingtons on a given hunt. Basically the same with the 221 Fireball verses the 222/223. You loose a little velocity and so PBR, but not enough to worry about in most hunting situations.
For the Contender's I have Bullberry 14" and 20" 17M4 barrels and 14" and 20" 17 Rem barrels - and a TC factory 21" 17 Rem carbine barrel. Have bolt rifles for both cartridges as well.
