Pitfalls with the Singer 500A Rocketeer or a White Rotary? Nah, only that they're addictive
. I have two 500As and several White made machines. I like them all.
The Singers will need lots of internal cleaning if they're gummed up from sitting. I've had to use Denatured Alcohol and Hoppe's #9 on the inside of mine. Both were gummed up almost solid. After getting them freed up sew with them using every cam position and floating the moving parts with Tri-Flow. Once they're loosened up use them occasionally and keep them freed.
If you pull the cam stack to clean it and the gear under it as well as the plunger to the bottom left (recommended) there is NO need to take the cam stack apart. It can be cleaned with a tooth brush and a small bottle brush while assembled.
As for the White Rotary, they're a good solid simple machine. Only odd thing is they rotate opposite the Singers.
Joe