I'm about to start a 1/2" engineered staple down( birch 3 1/2 w) and the installation recommend either a 1 inch senco 19 gauge or Bostitch 20 gauge staple. i'd prefer to use 18 gauge spot nails or bostitch. Any insight into potential issues with a heavier guage staple.
Thanks

My Senco staples, fit and work in the Bostich floor runner.

I usually go with what the manufacturer recommends.

Depending on the construction of the engineered floor, there is always a risk of surface dimpling, the heavier guage of fastener you use.
If the manufacturer recommends a specific fastener, you better use it, so that you are not the only one guaranteeing the floor.