It is true that Gmail should stay under beta.
I have a Gmail that is pretty fully loaded with 99% sometimes and some other days with

You are currently using 2771 MB (96%) of your 2877 MB.

The problem that occurred today is an email that I receive from the same person at least 4 or 6 times a day, every day. But today i just checked that Google Gmail Beta put this person email under my spam folder.

Gmail should be careful about this feature because sometimes you can end up deleting your bulk spam emails without checking each name.