I'm don't know if the 35 Remington is that much more effective than a 30-30.
However, an Alaskan fisherman I personally know, dropped a grizzly during a charge with 2 shots out of his 336 in 35 Rem......pretty effective.
As for the Remington pump, I prefer a much more capable cartridge in the same package, I own a 7600 in 30-06 (and a Rem 740 semi-auto in 30-06 as well).
I do not reload, so for my lever action I did choose the 336 in 30-30....you can find ammo everywhere....not so for the 35 Rem.