The 270 Redding is a mildly improved .270-08.  It is very much in the same class the 260 Remington, 7mm-08, 6.5 Creedmore, et al.   

While people might get within 100 fps of a 270 Winchester fired from a 20" barrel, keep in mind that much of the "data" for the 270 Redding comes from people that load it until the bolt sticks, back off a tenth of a grain and call it good. 

The hard fact is the 270 Redding has a case capacity about 3% greater than a straight neck down.  It hardly seem worthy of the fireforming.

Performance aside,  the 270 Redding has a couple more issues.  The increase in shoulder angle is partly achieved by pushing the neck-shoulder junction back.  This is a recipe for doughnut issues. 

In addition the shoulder is moved .050 forward. I don't have a magazine in front of me at the moment, but I seem to recall a rib inside the magazine just in front of the shoulder to prevent cartridges from moving forward under recoil.   While you could modify the magazine to remove this rib, why do it for .050"?  Why not .100" .150" or .200"?

A wildcat or boutique cartridge should be worth it's keep.  I don't thing the .270 Redding is it.  It might sell, but you'd be selling the sizzle, not the steak.

I'm not against wildcats per se, just going through the effort for negligible gain.  You could simply fireform the 270-08 with a 30 degree shoulder headspacing of the neck-shoulder junction and have more case capacity than the 270 Redding.

The issue of improved performance with semi is always going to be the magazine.  Here you are limited to about 2.80" +/- .020 in OAL and roughly the same case diameter and taper as the .308 if you want to maintain full magazine functionality.  You could do something like the 6mm Remington or .257 Roberts with the shoulder improved and moved forward assuming magazines are altered and there are't unforeseen feed geometry issues.

A blown out .257 Roberts would be much closer to the 25-06 in a 20" barrels than the 270 Redding would be to a 270 Winchester.

short version.   All the wildcat rifle cartridges are is the rifle world version of Glock vs. 1911 or 9mm vs. 45.   you buy your ticket and take your ride.

   you buy your ticket and take your ride.

You forgot get back in line.  Then you start sneaking rides after the park is closed.  Finally, you just get a job at the park so you can ride 24/7.

short version.   All the wildcat rifle cartridges are is the rifle world version of Glock vs. 1911 or 9mm vs. 45.   you buy your ticket and take your ride.

I'd never bother arguing the merits of wildcat vs. factory. I'd find things to love about each. The way I see it, if a small handful of people like something and are willing to pay extra to have it in their lives, that's reason enough for the cartridge (wildcat or otherwise) to stay on life-support. My opinion, of course.

Hell, if I could get a barrel for a Baby DE or a Tangfolio, I'd be carrying a .41 AE! 

One thing the .270 does for you, is to give you a very wide selection of very good hunting bullets to chose from.  It's very accurate as well, and with less recoil than a .308, and a nice flat trajectory.  You get less issues with loss of internal case volume like you do with the .260 Remington and you still keep decent bullet weights for larger game, unlike .260.   
What you lose though is the large selection of cheap FMJ rounds. 
7mm-08 is still a great round, and one of my favorites.  In fact, over the last two years I've been selling more and more of them to hunters in light and handy bolt actions.   A semi auto would be excellent, especially if it was something like a Broadsword which has almost no recoil at all.