re: .270 vs. 30-06

I shoot a 30-06 and can say that I've never lost a deer that I hit. my dad shoots a .270. Lost 2 since he's had it (about 12 years).
Last night I got a call from a co-worker that shot a good buck at 150 yds with a 270. had some blood and wanted me to bring my dog. Well several hours later we've gone 500 yds on blood and never found the deer. Lost blood and were in a MAJOR sawbriar thicket. The dog acted like the deer was in there but it was so thick we couldn't see but about 5 feet in front of us in the dark... even with big flashlights. He's going back to look today but I don't know if the deer is dead.

Since I've had my blood dog he's been on a .243 and .270 trail 3 times.... never with good results. guy said he was shooting a 140 grain bullet. maybe it was a bad shot or maybe the setup just doesn't have much knockdown...... I'm not sure but I do know I will not be trading in my 06 for a 270 EVER.....