RE: Is this true?
Not true as deer rifle they are all pretty equal. Where the .270 gets some flack is being used for elk and moose as bullet selection is a more limited in .277 cal vs .308 cal. Though in reality with todays choice for the hunter in regards to bullets it can be used as effectively with proper placement, bullet and some limitations...speaking strictly for larger than deer. For deer ain't a hill of beans difference between them.
I have owned a 270 win since i was 13 it has been used to harvest antelop, wt/mule deer, black bear, elk and moose. I did have some stipulations with the larger game such as solid bullet construction, positive shot angles to the vitals and reduced range 300 was my limit. I have since switched a few times my all around rifle and now use a 7mm rem mag as it gives me everything I need without the limitations put in place. So if you were buying a rifle for larger then deer i'd say 30-06 would be the better choice. For upto deer it don't matter buy which ever floats your canoe!!
Lethal you should put the 06' in back up duty and buy a 7mm rem mag, we hunt similar terrains and game it does a bang up job IME. I have taken antelope to moose with it as well. That is if your like me and actually like one rifle to be your go to, if not then look at the 25-06 for your deer rifle it is a real bute!! To close of a call with 270 and 06 imo to make either one better for deer.