* No need to use DMS, cron emails you the output of your tasks anyway. A three-line script can be used to "only email on error".
* The proposed pricing model goes against everything that tarsnap stands for, charging arbitrary amounts placing users in arbitrary ranges.
* The proposed pricing model means a 13x price increase for me (WTF!?).
* No need to be a sysadmin or anything alike to configure it. Granted, it's not for the masses, but for anyone in the tech industry, it's just a matter of RTFM.
Want something for end-users? Write a nice UI wrapper around tarsnap and overcharge that. Same backend, different product.