Hey Keith,
I agree with what you’ve said, all makes sense.
The thing I was most worried about was not so much the aspect of previewing the image/s, as like you’ve said, it seems to fair pretty well on page load with imgix and Amazon S3 - but the storage on Bubble set to 10GBs. I may have a owner upload 12 photos, possibly 5-10mb photos, and I was slightly concerned in the long run it would eat my data.
I know Bubble offers additional storage, but its an extra $10 per month for an extra 10GBs.
With this said though, I am using Croppie and with the latest release 1.2.0
It seems to let you save and specify the quality for some slight compression. I’ve yet to test, but hopefully this can bring the file size down a bit, if so I’m very happy 
Sometime this week I will test and post my findings if anyone is interested…
Cheers,
Luke.