Analysis paralysis is common, and I don't think a bad thing to a point. Machines are not cheap and for many of us we don't know what we don't know so dragging your feet some is perfectly normal before making a big purchase like this..
Too small is a real issue, and is often emphasized. Too small makes things difficult to impossible, but too small is relative.
I started out with a Sherline mill, the table is 2.75x12", 12" spindle to table, and weighs 50lbs so it is a very small mill.
Lots of people warned me it would be too small, but I didn't have the space for a bigger mill (or so I thought) and it has done a great job for the projects I was interested in when I bought it. The only problem I have had with the Sherline, is my interests grew. Even though I know have larger mills, I still use it quite a bit for my smaller projects.
The Clausing is quite a bit larger than the Sherline, but in the big picture it is not a large mill (roughly comparable to the many import 7x27 mills, including the PM-728) . It happens to be about the biggest mill I could manage in my space and luckily has worked for me.
I have a small space and mostly make small things, I'm not fixing farm equipment or other large items. The closest I've come to it not being big enough, comes down the the vise that fits being smallish, which means coming up with work arounds, more effort, but gets the job done.
The size of the mill also impacts the size of accessories, vise, rotary table, dividing head etc. When I got it, it had a 5" vise which is too big and limits the full range of table movement. I bought a 4" vise that is a better fit, but having that 5" vise has proved to be useful so I've been glad to have it for a few jobs that pushed the limits of the mill. Fixturing to the table is more difficult, but would allow me to work on parts too big to fit even the 5" vise.
What you see mentioned far less often, is too big, but that is also a thing particularly in a small space. You have to live with the mill, and a mill that is so large that it makes working in your space difficult, will not make you happy. There have been people on this site who bought the biggest mill that they could fit and have since expressed some disappointment and a wish that they had gone with something a bit smaller because it impacts the utility of their space. It is not as common as people unhappy with too small, but too big exists.
A lathe is pretty much contained within its foot print, by contrast a mill needs space side to side, and a smaller amount in front to allow the table its full range of motion. Many mills also require room for the head to move, possibly side to side, and room to the rear. This creates a lot of dead space around the mill. With some planning the space can be worked with, but it is a factor. Mills are also quite tall, many in excess of 7 feet which can be an issue with ceiling height.
Using my Clausing since it is what I have.
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I have a small space and a low ceiling with a hard height limit of 76". This only leaves 4" over the mill and eliminated many mills including the 932 from consideration (81" tall). I also have to make the most of my space so I used the dead space behind the mill caused by the long overhang of the head for storage shelf. Similarly I use the dead space on either side under the table for storage.
Where it becomes hard for others to advise you, is you know your space, and you have to live with the mill. You may not know exactly what you are going to make with it, but you have a better idea than we do.
Too big is not good, but I think most agree too big is better than too small. Just right is ideal, but a very hard target. Most default to the what is the biggest you can live with.
The 932 is a solid choice, but If the 728 feels like a better fit for you, that may be the right way to go. It is a nice size for many.
The PM25 was very high on my list of options. The 728 wasn't available at that time or it would have made my list as well. I was where you were, second guessing my options when the the Clausing basically fell into my lap. I was lucky to know the seller, who had bought a Bridgeport and was getting ready to sell the Clausing when I happened to ask about mills. It was too good an option to pass up which made the decision easy even though it was about $1000 more than I had budgeted for a mill.
