Well, I have both, so I hope I can help. The .30-06 is a very good round and the .270 as you said is a -06 trimmed down to a .270 (a .277 to be exact) calliber. The most popular .270 bullet weight is 130 and I use a 150 grain for my .30-06. The two, if you are hunting, are so close there isn't a whole lot of difference. But the .270 has a couple of advantages to the .30-06 it doesn't kick as much, it shoots flatter, and has a higher sectional density (.242 in 130gr for .270 vs. .226 for 150gr. for the .30-06) I forget what the BC of those two are, but I think the .270 does have a higher, I'm not for sure though. What would you be using for?
If I had to choose one I would pick the .270 because it shoots flatter and gives less recoil, but the two are very good cartidges, they will be around for a very long time to come. You can't go wrong with either one, is what I believe.