I know there have been topics on this and I have read several but yet i still can't find a definitive answer. Will size 10 boots fit the Union SL M/L size? Or, do i need to go to a L/XL? I ride a proto ct 154 for what its worth.
Why would the board matter for this? What is relevant is the boot - and with a size 10 you will almost certainly be ok with M/L size bindings.
Worst case get the M/L size binding but with L/XL size straps or with the longer strap extension.