Hi,
Not all campgrounds have 50 amp service. If a 30 to 50 amp adapter is used, be prepared for lots of "load balancing" issues (i.e. you can use the air conditioner, but not at the same time as the microwave). I'd certainly add an autoformer to a 50 amp unit.
Surge protectors or energy management systems are a VERY good idea on a 50 amp RV. They are not needed nearly so much on a 30 amp system.
Some 50 amp high end units will come with an energy management system that may mitigate the need to be aware of what is being run.
The basic difference is that a 50 amp RV has two "legs" of power--each one is 6000 watts. A 30 amp RV has a maximum of only 3600 watts, but will be designed with that level of power "in mind".
Since my 30 amp class C was out of warranty when I purchased it, I've made some upgrades allowing me to use up to 65 amps, by using auxiliary shore power cords in addition to the OEM 30 amp.
The real answer boils down to your camping style. If you plug in where there is only a 15 amp circuit (for example at a friends home), then it may be better to have a 30 amp rv--rather than a 50 amp (which is really 100 amps).
If you plan on always being in commercial campgrounds then 50 amp allows more flexibility (at least until the warranty period is over).
If you choose 50 amp, immediately add an autoformer and a top of the line energy management system from progressive dynamics.
If you choose 30 amp, then probably those two items are not a needed expense.
Since I most often boondock 30 amp meets my own needs better.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.