Hi!
It seems you are in the same boat as me. I ordered the yincrow calf for starters. They are similary priced and seem to use the same shell.
I'd be interested in your assessment of the rhino, when you get them!
Chances are you will love them, I especially like the cable on the calf, it is light, soft, no microphonics and does not tangle too much. (Guessing the cable on the rhino is very similar...)
I too have ordered 2 cheapo sets to check the fit of the mx500 shell for me.
My choice fell on the faaeal Iris 2.0 and 2* the vido earbud. Apparently Vido/yincrow x6/nicehck traceless are all the same earbud or use at least the same driver. The main difference being the price...
Rigokoudoku did a review of the faaeal iris 2.0, where he compares it to a bunch of other cheap earbuds. Might be helpful:
https://www.head-fi.org/showcase/faaeal-iris-2-0.25338/reviews
I ordered the Iris 2.0 for 5€-ish.
If you have bigger ears it might be an idea for you to also order some silicone rings to enhance the diameter of the rhino. I did not get a good fit with the yincrow calf at the beginning...
In any case let us know what you think about the yincrow rhino, once you get it.