Will you get pleasing images with either of those scopes? Yes.
Will they be too small? No. I use a 60mm because it's small and gives a wide FOV.
How much is your image affected without a FR? Follow Barbarosa's link to Astronomy.tools FOV calculator and spend a lot of time framing the objects you are interested in with different OTA/camera combinations. It will be your best friend.
Will it be unsatisfying? Hardly! In fact, it seems that many people start with long focal length OTAs, like an 8" SCT, then pair it with small sensor cameras like the ASI224 or ASI385, only to find that the FOV is very small. They then add either a small aperture OTA like you are suggesting, or a larger sensor camera, or both! (that's exactly what I did ) The ASI385 works well with the AT60ED, but the larger FOV of the 533 is even better. More than just being a decent setup to get started, it has become a favorite tool for quick and easy wide FOVs and some of my favorite viewing is with this portable setup.
You can use a small aperture OTA with or without a FR. Surprisingly, my F/6 AT60ED works great with an F/6.3 SCT reducer giving me something around F/3.8. I add a flattener when at F/6, but it's not necessary. You can always do that later. I'm not concerned with the speed of the systems and base all of these decisions on the FOV desired for the target. The larger the FOV, the easier it is to get started and have quick success. It is a highly recommended setup in my opinion.
Here are some examples of images taken with an AT60ED and ASI533. The first two were at the native F/6 and the others needed the FR for approx. F/3.8 to better fit the object.
With a good mount like the GEM28, I would not hesitate to put a small refractor on it and start having a blast!
(click for larger image and details)
150x 8.0s 1200s
IC 1805, Heart
61x 30.0s 1830s
NGC 1499, California
80x 30.0s 2400s
NGC 2237, Rosette
90x 30.0s 2700s
Edited by chilldaddy, 16 September 2021 - 02:57 PM.