FWIW what i’m saying here is that we will not be intentionally deleting them just because.
However we are not asking for new nikon samples with different crop, as you can see in Of the following brands we like to have: on https://raw.pixls.us/
Like i said in previous comment, i don’t think that is up to r.p.u to decide.
Right, I did not notice that.
I just noticed something else though: rerunning lftp again I get tons of lines like the following:
Removing old file `Nikon/1 J2/DSC_0451.NEF'
Transferring file `Nikon/1 J2/DSC_0451.NEF'
It seems that basically all files get re-downloaded. Maybe the creation / modification time stamps all got accidentally updated somehow? Am I the only having this issue?
The data dir gets rebuild once a day. To build it i use the cameras.xml from rawspeed to get the normalized naming of makes/models. To reflect updates i just rebuild the datadir. Though, filedates remain the same, only directory dates change. I suppose you can tweak lftp only to mirror if the size is different.
Worksforme with lftp -c mirror -c -P 4 -v --delete.
You said you have old lftp version. Perhaps that is the reason.
Or, storage fs? 
For what it is worth: --ignore-time does help, getting the newest lftp does not. The only explanation I have is indeed the ‘ugly’ fs (FAT32) ;). My space constraints leave me no other choice, though.
By the way: I therefore still can’t store the two GITUP files with ‘:’ in their filenames.