once old a's die out from only lasting 1-2 months for some riders i will Laugh Out Loud when you ride pro's.
a pretty good solid old a last cary around 3-4 weeks maybe 5-6 if hes smooth. thehehehe
Differences between A and B / Pro Models :
A: Small, Compact, Light, Tend To Bend Easier And Bow Causing Scraping on banks, roads ect. If you have size 13 + Shoes your foot takes up the whole deck. Decks seem to be strong but once they get a the slightest crack they can quickly downfal into death of the scooter.
B / Pro's: Higher Off Ground, Dropouts tend to bend makeing it difficult to put in the back wheel. In my opinion pros are alot stronger becuase of the folding mech not only being welded but is also bolted. the pro model brake tends to either bend or brake or wear through depends what your doing.
My Opinion
Pro / B model it will last you longer, more for your money. (unless you somehow FIND a old a just dont steal from a 4 year old.) 50+ Dollars for a pro is worth those minor problems.