They could have grandfathered the existing accounts for at least 6 months or so, but giving any user -- whether a paying customer or a free user -- only 30 days to start paying $100 a month when many of them expected to be paying little or nothing for quite some time? Well, I think that is the height of arrogance and disrespect for the customers on which your business is built -- and an exceptionally effective way to alienate all those free users who MIGHT have become paying customers if only they had been given a reasonable amount of time to adjust to the change ... or even a reasonable new rate for small volume users.
Why not offer something like $5 a month for up to 10 subscribers instead of basically kicking all their free users in the groin? Most small businesses would not bat an eye at such a small charge even if they had only 30 days to start paying or abandon Chargify. But did they offer such a service?
No, the fact remains that the guys at Chargify appear to be way too naive for any serious business to trust or rely on them at this stage of the game. They didn't "get it" when they made their blunder and from what I have seen they still don't "get it".
But no worries, there are others that will pick up the slack ...