I am really liking these forums, and it would integrate nicely with several of my current nodejs projects. However, I have a few questions which may tilt me either into supporting it or whipping out my own super-simple one, this mostly comes down to storage situation.
Great choice with redis from a performance angle, but without knowledge of exactly how you store things in it, I am moderately concerned with overhead. Any rough estimates on storage overhead per user/post/etc (any specs would be helpful). I run a custom fork of redis to do geocoding, so downgrading to one that supports virtual memory is not-doable. This means I would need the forums, my nodejs site, and possibly mongodb with its big memory mapped files to all fit within 2GB of ram. I am using both ramnode and digitalocean SSD backed boxes for hosting. This information would help me make a decision as to viability.
Also, where/how are you storing images? Are these being serialized into redis, or are they being stored onto disk? Whereas I can no doubt store a shit-ton of text within a reasonable amount of ram, I could easily see thumbnails or user uploads getting out of hand. Any information there would be more then helpful.
Finally, do you have anything to shard on, or am I going to have to figure out something else in that regard?