Absolutely. I trust Firefox Sync more than third-party services. I have a fairly comprehensive hierarchical structure. I only bookmark things I really care about, but even still have hundreds of bookmarks in tens of folders. It's useful because it makes these sites show up immediately in the address bar as I start typing. API done for example. I just start typing the library/API name and the address bar autocompletes the part to the doc index b/c that's what I've bookmarked. One step shorter than bouncing through Google.

I also bookmark articles that I think I'll reference in the future, that supports or contradicts something I believe strongly.