One thought I have is converting a sizable portion of old Canon CR2 raw files to adobe DNG since I've noticed that reduces filesize by roughly 20% for the files that I have. This isn't really a long term solution though and I'm actually kind of unsure of what to do. I keep hoping that I can hold out long enough until Dropbox's gb/price get's halved again. Then I'd likely be set for some time.
I really can't think of a cloud service for ~1.5TB of photos. Have you found anything that would suit your purposes?
I also use crashplan for offsite archiving of my photo library, but I really, really, like having the entirety of my photo catalogue accessible everywhere. Excessive, sure, but definitely nice.
With loom, I am hoping they integrate the jpg rendering of raw files into their photos views on web/mobile.
A benefit of Dropbox/Carousel (+ Lightroom locally), is I can fly through all 215GB via thumbnail representations without having to call the file explicitly. If there were some mechanism to offload storage to s3 or glacier, while retaining the nice UI afforded by the Dropbox/Lightroom clients, I would be all over that.
https://github.com/s3fs-fuse/s3fs-fuse
There's also Syncany for a more client-oriented approach:
Granted, Lightroom/ACR still do a very good job of rendering RAW files, so the difference isn't that great without pixel-peeping, but it might be something you want to think about when it comes to switching formats.
I've since gone back to importing the plain CR2s as my on-disk RAW format -- in practice CR2s are more universally useable than DNG files since not everything can read DNG whereas since you can always go from CR2->DNG, everything that can read DNG is covered by CR2s.
I definitely had bought into the adobe dng idea of it being the superior format for compatibility, but didn't consider there might be situations where something could read CR2 better than dng.
One of the advice I received was to batch export to JPG to have a small and easily sharable copy, and keep all the originals in Glacier or other cost effective backup that doesn't need to be accessed too often. I haven't done it yet but it seems to be a reasonable approach.