There are basically two types of 50 amp transfer switches.. One has two sets of contactors (Relays) and the "At rest" (no power) state is "Not Connected" when you plug in one set locks in and in so doing locks out the other set, When you start the generator, after a time out (usually 30 seconds to 1 minute) the other set locks in and locks out the first.. I can see an advantage to this but I also like the concept of KISS.
Intelletec models the "At Rest" (no power) is connected to Shore, when you start the generator, after the time out, it transfers.
There is also a 3-way transfer used on some rigs with Inverters (I actually suspect the 1st one is a 3-way, that would put the at-rest (no shore or generator power) mode "INVERTER" and make sense.
So unless you need a 3 way, I would go with the Intelletec type.
Page 2..... The only other difference is size shape and mounting, that is, the holes may be in different places or one make may be wider or thicker, so if it fits. it should work. Since the 30 amp switch is smaller physically the PO already drilled new holes.
the bottom line:
No need to worry about the make and model, they all should work the same, just worry about the size of the box.
Home is where I park it!