Extremely well designed framework. It can cover more than 90% of use cases in my opinion. I'm currently working on a project written in Scala that requires a lot of scraping, and I feel really guilty that I'm not using Scrapy :(
I've done something similar, you can just add a Pipeline (Pipeline Task? not sure of the right terminology) which posts off the data somewhere else. You can also then store the full item logs in S3 so you can go back occasionally and check nothing has been missed. Works an absolute treat.
In the project I work on we do have the usual periodic crawls and use ScrapyRT to let the frontend trigger realtime scrapes of specific items, all of this using the same spider code.
Edit: Worth nothing that we trigger the realtime scrapes via AMQP.