I would not cut it, if you are not too stuck on 25-06 trade it for a .270 or 30-06. plenty of these GBO folks would be happy to make you happy. If 25-06 is what you really want then cut it, but that length is special to only a couple select calibers. thejanitor
Anything the .25/06 can do - the .270 can do better - and with a shorter barrel length!
Actually I DON't LIKE THE .25/06 - but love the 'Roberts' and .250 Savage!
The advice about the .25/06 "shining" at 26inches is correct. And 24inches is a huge advantage over 22 in that round as well.
Twas me and I was looking for a long-distance shooter to shoot from a tree stand or other 3-4hundred yard distance,
I'd either choose the 7mm-08 or .270Win. Both do well with a 22inch barrel (and even better with a 24!, but don't come with that length).
If you need a 20inch 'stand gun,'
consider getting a .30-30 or .308W and chopping the 2 or even 4inches (I assume you reload and can tailor your handloads accordingly).
ADDED: I won't go into a big schpiel but cartridge "efficiency" and things like "expansion ratio," but those things are important when considering barrel lengths versus compact tree-guns. 
A .308W with a 20in barrel is still a good 300yd shooter. A .30-30 with a pointy bullet could also do many things better than with a "blunt" carbine bullet.
Keep the .25/06 for varminting and bench rest shooting, or sell it to someone who will use it for those things.