Sorry, no experienced based advice from me. But, here is some thinking on my part... I observe that solenoids are rarely seen in robotics. So, I think that is your answer. The question is, why?
There are obviously some advantages to servos. By the simpicity of their design, they are inherantly more reliable, and cheaper.
While most solenoids are on/off type devices, there are proportional types as well. But, most are the "hammering" type you mention.
Some solenoids are latching... a magnetic force holds it in position without power until a reverse current is applied.
I just thought of a large scale installation of "robots" that uses solenoids. I believe the Tiki Hut in Disney uses solenoids for the birds mouths. This quick motion of a light-weight object is one good application for solenoids.
And another application comes to mind... actuators for ultra-light indoor R/C Aircraft. They should be considered rotary solenoids. These are often home made coils with a magned mounted to pivot in the middle. Not just, on-off, but proportional control by controling the current provided to the coil.
In the above two examples, the solenoids are fast acting, but don't use the mechanical advantage of gears, so they are weak.
If I were to take the rotary solenoid used in the R/C Aircraft, and attach a gear to the magnet, then repeadly turn it on and off, I will have turned into a brushless gear motor. Conversely, if i take a purpose-built brushless gearmotor, then remove the gears, and only actuate it by applying a DC current, it will function like a rotary solenoid.
The same thinking can be done with a linear solenoid. If I stack a bunch of linear solenoids, and put one plunger in it, and then actuate the coils in series, I will have made a linear motor.
So, with the above thinking, they two devices are essentially the same, and therefore are likely to share the same force and efficiency.
The difference is if they are designed to actuate over a large range of motion, or a short range.
Joe Dunfee