rode 5.2s (lows) on an 8.5 with three inside washers, cant recommend it. if you really love small trucks and dont want to size up, it may very well work.
if you are accustomed to your trucks being .25 smaller/larger than your deck, its going to feel pretty weird and take time to adjust to. its worth depends on the skater and what you are willing to give up. wheelbite was more frequent, landings and hill bombs felt sketchier, less room to grind. flip tricks felt more compact and easier to throw but it was negligible/bad to me, i struggle with landings if im not fully focused. went up to 5.6s and had a much better time.
if you have the trucks available its worth a shot but definitely dont buy new trucks for something like that. ended up being a waste for me because i dont ride anything less than 8.5, had to sell basically brand new trucks for little return. at least i know better