Yes you can.
There is a small FPS loss when using blueprints, but not so much that you as a indie or small studio developers will have to worry about.
When you make a AAA game using only blueprints will make a impact on the game, but you will then probably have a team of sixty developers some of them coders.
Using the material merge feature will make a very larger impact on your FPS, more so than using only blueprints.
The largest problem with blueprints is that it can get confusing, however the Function and debug options outweigh the negatives.