Well, the twin button is actually different (see pic below). The one I'm considering is the triple (as per OP), also because with a single engine that's all I need (on one stick obviously).
Either ways, why do you say it's not as clean as an integreated unit? As I understand, there shouldn't be any difference between units ordered with twin or triple from the beginning or retrofitted. You can also choose the colour to match your existing throttles...

As another thought; I run with a single switch on each of the port and starboard throttles. The port side switch controls both drives. The starboard side switch controls just the starboard drive for fine tuning.

Tab switches are on the dash & they hardly ever get used.

I wish I could say that for my Fever 27, but they're really necessary to get on plane, and some fine tuning is useful also while cruising - hence my idea of having also tabs switches on the throttle.

Besides, I don't think it's possible to fit a switch on both sides of ONE throttle.
Though I guess I could fit a second one just to show off a bit...

Because that is not the set-up I have. I have the dual trim button for thumb operation (integrated into the stick), but the tab buttons are bolt-on with the wire traveling down the stick. It's clean, don't get me wrong, but not as clean as a fully integrated system with no wires showing. Also, at the time, the only color the bolt-unit came in was black. My sticks are blue.

Is the one below the bolt-on switch you're talking about?
I've seen it in Livorsi catalogue, but it's only available for r/h throttles and mine is l/h, courtesy of Reggie!
But frankly, I can't say I like it, and that's not just a matter of wires arrangement: the layout of the triple switch seems much better imho, allowing to operate all 3 switches with the thumb and fore finger independently.
Otoh, I never tried any of these solutions, so what do I know...?

Close, but not the same. Mine are horizontal and next to each other and I can operate with my index and "you're number one" fingers. They mount the same way.