Well after you bolt them on then you get to dial them in. Which takes time and access to the necessary brass.
In one sense it's a trade off of time spent fussing and the $$ spent on hardware
fussing with the FI map, either directly or indirectly.
And then there is the added factors of carbs don't automatically adjust for altitude nor the change of seasons really all that well. And having spent the time and effort to retrofit a set of round slide carbs on my R65 and then live with them, I know that dialing in the EFI using the targeted modifications we are working on will be WAY easier on every level, and will be less costly and easy enough that anyone who can perform routine maintenance can make it happen.
And did you notice that those cams are horsepower cams, not mid range torque cams? So while this may provide a top end speed boost you will loose low end and some mid range power. Which some may desire but it wouldn't be the best choice for going slow in the dirt.
At one point I did consider yanking the EFI on my 1150 and installing some decent slide carbs, even though it is a PIA to get them dialed in and then have to fuss with them as the seasons change. But with these mods I don't have to deal with all of that fussing. Its much more of a set and forget and enjoy the ride instead of noticing engine responses that shouldn't be there in the first place.
Like Poolside sez, a properly dialed in EFI is invisible, you don't even know it's there.