Whenever you introduce bellcranks into a system, they add additional connections and connections allow slop. Ain't a big deal if you know about it and can rig connections with minimal slop. And of course you have to keep an eye out for wear. whatever..........

The bellcrank shown works ok, but actually isn't as good a solution as a Y pushrod from one servo. You've got to do significant work to place the bellcrank. Do the same or less shaping a custom Y pushrod and you've got the same functionality with no added connections and very slightly less weight.

If that bellcrank does not have a way to change it's shaft length it won't be easy at all to place in your aft fuselage. It will need to go where the plates match up very closely to the width of the fuselage. And if the two attaching plates are rigidly parallel to each other they're not going to fit most fuselages. Most are tapered. So there are a couple of issues to face as for an easy installation. I'm not going into every possibility and solution, but am going to suggest you think about how that sucker could be installed in YOUR airplane.

And then consider how much less work it'd be to create a Y connector.