Expired Tumblrs - Change to Https or Not

The default setting in Tumblrs as you all know, is "https". The question is...

When we re-register an expired Tumblr with good stats (PA/TF/RD) on "http" is it good or bad to change it to "https"?

Keep it on the protocol where most of the links point. If most links point to https, then switch it to https and vice versa.