If you fetch a page by submitting a form with the HTTP method POST, and then you try to refetch that page, OmniWeb runs a sheet warning you that to get the page again, it'll send the POST data again. So far, so good; I think this would be a bad feature in a mainstream browser as 99.8% of humanity aren't going to understand the question, but clearly OmniWeb isn't a mainstream browser.
If instead of cmd-R you do cmd-shift-V, you get the page source, without another roundtrip to the server. From my point of view this is good.
If you do cmd-I, then click on the outlineview item for the page source itself, then click view source, you always trigger a roundtrip to the server, without any warning sheet. I think this is bad, especially as I like OW's page inspector feature.
A site which can be used to display this behaviour is
https://connect.apple.com/cgi-bin/We...MemberSite.woa. My apologies for the presence of the promotional picture of some old geezer on the first page after logging in -- it was while investigating said picture that I encountered the OW behaviour which I'm reporting.