I have a 913d3 driver with a regular flex shaft. Any issue with changing to a more flexible shaft?

I have been looking for a 19 degree 915h hybrid with a regular flex shaft. They all seem to have stiff or very stiff shafts. Any issue with purchasing on wit the stiff shaft And replacingbthe shaft with a regular flex. I have a 21, 23 and 25 degree 915hs and hit them well. Or should I buy another 21 and change the loft.