Kaben, a 5 spoke isn't automatically fast.
Here is a 5 spoke that can be had for $500 new and comes in front a rear. Why don't people buy this?
Ask yourself, "If 5-spokes are fast, then why don't triathletes and road TT specialists use them?"
80mm deep lenticular wheels are
proven (with wind tunnel "receipts").
Front discs can be
very difficult to manage even with moderate wind gusts. They can be helpful in ideal conditions...and detrimental in less-than-ideal conditions (read: make you
slower).
I think I'm gonna sponsor a proper scientific study to articulate and enumerate how "fast" a 5 spoke really is. I'm surprised that no one has done this being that the IO is
literally the most expensive bicycle wheel on the market at $4,000 USD.