First off, SUP boards do not work the same as a surfboard. To navigate it, you need to use a paddle whereas you do not with a surfboard. But, you can still technically “surf” with a SUP board. Truthfully, though, it depends on what you consider surfing. If you are just referencing riding waves, then a SUP board can handle that just fine. However, if you are talking about ripping through 10-foot monster waves like the pros then you may be disappointed.
When it comes to hardcore surfing, there are some limitations that SUP boards possess. One is specifically attributed to air-filled models and they will bow slightly in the middle. When needing to gain an excess amount of speed, the bowing in the middle will affect the board when it hits the wave and will not ride like a surfboard. Secondly, when you ram into a wave, due to the air, it will not react as a hard surfboard would.