My own personal opinion (yes, I've owned an old Marlin .30-30 years ago)....

.30-30 --- Tried and true, historical, close range, rifle. Everyone has shot a .30-30 over the years and/or owned one or knew someone who owned one. Perfect rifle for close range, thick woods. Guys still carry the ancient .30-30 in the heavy woods of the George Washington Nat'l Forest here in Virginia. In a nutshell: The ol' .30-30 will never die.

.270 --- Way better cartridge than the .30-30 and has a way longer range. The .270 is for more open areas, high ridge tops overlooking a cut cornfield or something. If you want to reach out and drop a deer at 200 yards, the .270 will do just fine. The .30-30 will do it, but, you'd really have to compensate for the huge bullet drop. In a nutshell: The .270 in fact, blows the .30-30 away, as do most bolt action rifles. But then again, I don't think the .270 (or any scoped bolt action rifle) can come up to the shoulder so easily and so quickly, as an open sighted .30-30 rifle.