It is slightly shorter but it has caused no problems. In fact trimming is not an issue because of the shorter case. I still load to near maximum bullet length and have had no problems with bullet retention. The shortness is in the neck, not the main case body.
Having fired a few hundred rounds from 06 to. .270 cases I have not had a shoulder separation problem. I have been doing this little operation since the late 60's.
I am aware that when you radically reduce neck size you can have more problems. The more pronounce problems show up when you start reducing neck size from .30 caliber to .243 (308 to 243). Neck thickening becomes an issue. I have not reduced from .30 cal. to .25 cal. I suspect that there are limits in caliber increase or reduction when the working of the brass is more radical. Reducing to .264 or .257 caliber maybe the point where annealing the cases become critical. Annealing may become an issue when reloading cases after "x" number of times, be they standard factory cases or custom made cases.
A more radical case forming process that I am involved with is creating .300 Savage cases from 7.62 NATO machine gun cases. I first run the case with a 30-06 full length die(Lee) to punch out the crimped primer and resize the case walls. I then run the 7.62 case thru a full length RCBS Small Base .300 Savage die. I then trim the case to the proper length. This has provided me a life time supply of good .300 Savage cases. This has been a very successful process.
I need to drop a dime on my brother who has a number of custom rounds he reloads. Many of them are based on the .284 Win. case and the 30-06. I will check with him because he may fire a few hundred rounds a month. A living breathing, practicing serious reloader.
I must admit that in my learning stage with factory cases I created some ugly loads in the beginning. But I try not to repeat those errors. Oops did I say I maybe imperfect.