I have been running for more than a year a periodic custom SmartApp which sends selected log events through one or several emails. Since ST retention is only 7 days, I send those Log Dumps every 5 days, soon enough to reactivate the SmartApp if its schedule fails.
Since I use those Log Dumps for statistics purpose, I send them as attached files, formatted for Excel retrieval.
I did recently update my SmartApp, migrating from Mandrill email web service to Mailjet, an alternate free web service (starting April 27, Mandrill will now cost a minimum of $360/year).
The main drawback of this email log dump solution is that some emails never get delivered (spam black lists on the recipients POP side), thus I use 3 recipient mailboxes from 3 different providers, hoping not all 3 blacklist MailJet SMTP servers at the same time.
And as for any periodic SmartApp, I get very poor reliability from ST cloud, scheduled SmartApps activations failing about 20% of the time…
Had I been aware of the “forever retention option” for $5 a month, I would probably have used it and saved me a lots of grief… 