@pth over 6k new users on just one instance this week alone. (Mostly refugees from twitter who are all engaged users who are used to best of breed clients)
I think that next 100k users is going to happen quicker than you think.
I’ve been on this service just a few days (ignoring the account I made months ago and lost the credentials for) and already have 5% the followers i had on twitter that took 12 years to accumulate.
This place is booming.