My dad got his main hunting rifle rechambered to .270 wby years back. With a muzzle break it's quite novel to shoot. Great round, I agree, especially if the barrel is 1:8 - 1:9 twist. .277 has suffered a limited bullet selection for years, and though more heavy for caliber options are available now, .277 still lags the mainstream. Most .270 barrels are 1:10, and like 130-140gr bullets. At that weight .264 WM has a better B.C, and much cheaper brass. The same could be said for 7mm RM using 168+gr projectiles.
Small bore magnums confuse me a bit. So does shooting a 165gr out of .300 magnum. All other things equal, a .270 Win will give up ~100yd of effective range to the wby. The .257 wby is better to 500yd, the 7mm rem mag (or wby) is better at 1000. For someone with intermediate needs, it's the goldilocks cartridge! Right between the .270 win and the .270 AM (necked down .338 LM).
For me personally, if the .270 win is not enough, I'll be taking a real step up to 200gr+, .30cal+ and ~3000fps MV. If I'm burning 70gr of powder, well, bigger bores and bigger bullets simply use it to greater effect.