Basher said..
I have the S-1s because they are better for wave riding in onshore conditions.
This is really about the apparent wind in different wave conditions. If you sail in wind that is cross-shore to the wave, or cross-off, then you get the wind increase as you go down the line and you need to dump power - and the Blades are best for that.
But in onshore conditions you often lose wind power as you go down the lane and the S-1s tend to help in that situation, delivering constant power and being less top-end orientated. The S-1s also give you a bit more back hand feel to crank the turns - or more 'response'. With the S-1 you can also tweak the feel with minor alterations to downhaul and outhaul.
Despite all this detail, you can still use the S-1s for general use and blasting about! I love my 2022 versions!
The Blades are also slightly more forward-pulling and so that, along with their more neutral feel, makes them popular for general blasting and perhaps better for jumping on the way out. The extra batten is probably also useful in the larger, 5m+ sizes.
The Pro Blades vary a bit from the standard Blades in that they have a bit more power for the equivalent size.
I haven't tried the Pro S-1s recently but I understand they feel much the same as the standard ones, in terms of power delivery.
Thank you, I'm a mediocre wave sailor at best but this was a really good explanation of how cross/onshore conditions and sail selection matter.