John,
First off, thanks for the info on the Sirui L10. It looked so interesting that I have ordered one.
Perhaps we have different perspectives, you as a photographer using long lenses whereas I use monopod and tripod with bins and scope. The thought of putting the Sirui on a panorama base was as an alternative to a 2-way video head for use with a scope, but I guess the combination would only save about 200 g against a decent video head and would not be much cheaper.
The main motivation for ordering the Sirui was its Arca Swiss compatibility, as I have a Berlebach 552 (IMO the best lightweight video head) on my tripod. I agree that a pan function on a monopod is undesirable but a tilt head is not only good for views above the horizon but also gives me a few cm more height. Most monopods are too short for my 190 cm (6'3"). I have used friction ballheads on a tripod with a scope but they are a distant second best to a video head and I can imagine that the lateral tilt would be a real PITA on a monopod.
My monopod btw, is a Manfrotto 685B, which can be instantly extended with one hand to the desired height and locks there. A grip release collapses it again. The Monostat is often recommended because the friction of its big foot damps out yaw but the sections of the 685B, which can rotate with respect to one another, offer enough rotational friction to provide a very steady view with bins. Not sure though if this would work as well with the higher moment of inertia of a camera with long lens.
Will report back when the Sirui arrives.
John