Untwised is meant to solve all problems twisted solves but it does it in quite a different way. They are two different tools that would solve the same problems using different approaches. Untwisted doesnt share code nor architecture with twisted. In untwisted, sockets are abstracted as event machines, they are sort of "super sockets" that can dispatch events. You map handles to Spin instances, these handles are mapped upon events, when these events occurs then your handles get called. The handles can spawn events inside the Spin instances, in this way you can better abstract all kind of internet protocols consequently achieving a better level of modularity and extensibility.
That is one of the reasons that sukhoi's code is sort of short, it is due to the underlying framework in which it was written on.
The throtting can be set directly from untwisted reactor(planning to implement soon once i get untwisted on py3). I think the support for caching is really good too, i plan to implement it this week.
Try to imagine how to solve the second example of the sukhoi README.md using scrapy, you'll notice you'll end up with some kind of obscure logic to achieve that json structure thats outputed by the second example in sukhoi's README.md.
The way of how you construct your json structures in scrapy it is different, scrapy has a longer learning curve too. It seems sukhoi has got better results in performance too.
This one doesnt look to support lookahead/lookbehind nor it outputs valid inputs for the matches though. However, it is interesting the way of how you chain the VerEx to build the patterns.