It's a complicated mashup of my index/crawler, structured crawls/dumps from crowd-source sites, live vertical APIs, and highly modified BOSS (edited, re-ranked, merged, omitted, etc.). The BOSS piece already uses Bing as a backup and could easily use Ask as well.
I have to projects, one kind of a side project and one a main project that would benefit from BOSS integration but I am not confident the service will be around in 12 months.
Bing API is equally simple and response times seem similar, so at first glance they seem to be somewhat interchangeable. But I haven't uses Bing as extensively as BOSS yet.
I'd be really interested to know your thoughts as well when you get into it. So please keep me posted.
I'm curious...how long did you spend making the first rev? Also, about how much have you had to invest in the infrastructure for web-scale searching? Are you crawling in the cloud?
About 6 months before I launched something, which was really a MVP, if that. I've invested in infrastructure, but not a ton. I crawl some from the cloud and some from my own machines.
I classify it as a search engine. I'm in to doing whatever produces the best results. I started with my own crawler before BOSS existed and then switched that piece to it (highly modified of course) to concentrate on where the marginal benefit lies. Techcrunch initially classified it as a "hybrid search engine," so maybe that is a better term?
