Actually, from Rails, to ASP.NET MVC, to ASP.NET MVC again ("because it was getting too complicated"), then to Rails. I'd also be very hesitant to use MongoDB

Actually, from Rails, to ASP.NET MVC, to ASP.NET MVC again ("because it was getting too complicated"), then to Rails. I'd also be very hesitant to use MongoDB as a main datastore as it has no durability model - the 'D' in ACID. I hope they've at least changed the setting, or don't mind losing their last 60 seconds of writes when their EC2 instance goes down. http://www.mongodb.org/display/DOCS/Durability+and+Repair#DurabilityandRepair-ThoughtsonDurability http://www.mongodb.org/display/DOCS/Durability+and+Repair#Du... Note that Mongo compares itself to MyISAM, but that is infrequently used now because of its lack of durability amongst other things - no transaction support, etc (most apps use InnoDB).