Small, quiet servo recommendations

I could use some recommendations for small, quiet servos, as well as a question about mounting them.

Is it okay to mount one servo directly on top of the horns of another? If so, can I use the same size servos or should the top one be smaller, and by how much? Should I reinforce the horn with a small piece of metal to provide added stiffness, or is the plastic usually sturdy enough to support the weight?

At the moment, I am looking at the following two servos in consideration:

Has anyone ever worked with or those particular servos? Do you have other recommendations you'd make? This is my first project of this type, so I don't have loyalties to any past company or brand. I'm looking for very tiny servos (less than 2.5cm/1" for the top one, and less than 4cm/1.5" for the bottom one if it needs to be bigger), and preferably fairly cheap as well (less than $10 per servo is good, less than $5 per servo is great - I need four, and another part of the project is a real moneysink, so I'm trying to save where I can). I know most every servo makes noise of a sort, but some are louder or higher than others (I've heard digitals can whine, and high squeals bother me more than low hums - the "mosquito tone" is a valid weapon here).

Torque and speed are low on my priority list. The absolute most I would ever need the servo to manage is 100° in 1/4 second, and that is a very extreme case - most turns will likely be 10° or less in the same amount of time, and I'm sure almost any servo could manage it. The whole weight on the bottom servo will likely be about 15g/0.5oz (dependent on the weight of the top servo), while the top servo only has 10g/0.3oz, so the load being moved is quite small. My primary concerns are size, noise, and cost - smaller and lower all around. What are your favorites to work with, and what would you recommend to me?

I’ve seen people stacking servos like that without any apparent problems. They’re quite sturdy things, and as long as you aren’t applying large forces I wouldn’t expect any problems. Can’t advise you which servos are going to be quiet enough for you, but you could contact any RC modeling forum for advice, or go to your nearest RC hobby shop to hear them for yourself. If noise proves to be a problem, you could consider wrapping them with something to deaden the sound?