I am not sure what a manley frame
Our manley frame size is the same as your medium.
They're not all that commonly used here. The most common (I presume everywhere) is fulldepth. A size we call wsp, approximately 3/4 height; and ideal, 1/2 height get use a bit; with manley/medium a very distant fourth place.
@omnimirage regarding frame supports this image is one I grabbed from one the pages you linked with some annotations added.
The red lines mark where there are two supporting rods that hold the frame up.
The blue line is where an ideal medium frame would reach to.
The green line is where a manley frame would reach to
The purple line is where a wsp frame would reach to.
https://www.ozbeegear.com.au/temp/typical-frame-support-bars.pngIf you experiment with some pencils under your own frames in similar positions you will find the full-depth and wsp frames work ok but ideal and manley frames will tip forward as they are supported by a single bar about 1/3'rd of the way along.
That is ok if the extractor is spinning at sufficient speed but not when it is stationary, starting or slowing down.
The 12 frame or larger extractors I've had a look at (here in oz) all appear to handle smaller frames as do the small tangential units and the locally made/horridly-expensive units; the ones you have to pay attention to are the 6 and 8 frame radials going around.
That's all about getting the frames to hold in pace while you're filling and starting it. Once it's up and running centrifugal support will hold them in place but.. eventually you will have a frame break in the extractor.
When it does your concern is not about supporting bars etc as frankly, you want the frame to be completely and quickly destroyed while you are you're hoping that the extractor is strong enough to survive the process without getting bits bent and distorted.
re" if I went and grabbed a super I'd have a spare frame after a spin"
I use 8, 9 and 10 frame boxes (and a mixture of full depth and medium/manley.. cos I can't help myself experimenting and I haven't really settled on what suits me). When I'm extracting I tend to have 2 or 3 boxes being processed not just one so I am extracting 8 frames at a time; not necessarily from the same super.
At the end of the process you will have a partially filled extractor to operate; and along the way you will have differently weighted frames. That's just a matter of paying attention to their relative weights as you place them around the drum although in a mathematical sense there are more options available to partially fill a 12 frame extractor as it is balanced with 12, 6, 4, 3 or 2 frames versus 9, 8 or 6 frame that have only 2 or 3 fill options available each.
re: "It's not obvious to me that they're from different extractors they look the same"
On the beekeeping supplies site the first picture has the motor mounted directly on the shaft
whereas the second picture has a a motor mounted at right angles to the shaft, driving through a gearing mechanism.
You ideal option is to hope you're buying the second one for the price of the first one :-)
https://static.wixstatic.com/media/55e9f1_bc5af77486a44be2887c322253d38805~mv2.jpg/v1/fill/w_900,h_900,q_85,usm_0.66_1.00_0.01/55e9f1_bc5af77486a44be2887c322253d38805~mv2.jpghttps://static.wixstatic.com/media/55e9f1_6a642415c0aa4f6c9c4174479d6b00de~mv2.jpg/v1/fill/w_759,h_759,q_85,usm_0.66_1.00_0.01/55e9f1_6a642415c0aa4f6c9c4174479d6b00de~mv2.jpg