Have you ever used giffingtool[.]com? What do you think of it?
Never used it and probably won’t ever (have a Mac and it’s a PC program so it’s impossible for me to test without using boot camp). Looks like it could be a good overall tool though.
Tumblr has a 1MB size limit and maximum width of 500px for GIFs. My main concern is it doesn’t look like it allows for much precision in regards to size limits. The program author says to reduce the width of the video file to 300px or lower. I try to get my GIFs at 450px to 500px wide and as close to 1MB without going over.
I wish I had some experience to base a review on, but I don’t. But just from looking at it, I’d say it’s a better tool than most and it’s as expensive/cheap as you want it to be (pay as much as you want). Good luck and thanks for the question