ignore mtime - or any metadata

[Hardy]

Hi,

SHORT:
rsync shall ignore differences in meta (inode) data, but does not even 
with --size-only. -- If in combination with --link-dest.
Is there any flag I missed?

EXPLANATION:
I use
rsync -avbuH --size-only --stats --delete-excluded 
--link-dest=/path/to/last "user at system:Shared/Data" /path/to/now

to sync backup-style and use the --link-dest option to minimize traffic 
(and space) and still have a full backup each time. So far nothing special.
Now it happens that at the source side data changes are moderate, but 
meta information (like atime, mtime) do change a lot. I didn't find a 
solution to make rsync ignore these differences to use a link. 
--size-only and -t (implied by -a) work ok with a simple syncs, but 
obviously (for me) it does not in combination with --link-dest. I can 
understand the motivation behind this: rsync is not allowed to change 
meta data of the existing inode, nor can it neglect the change - or can it?

Hardy