The comments have already suggested Xmarks to have different profiles, since Firefox Sync itself cant have them.
I, myself, am used to bookmark every single page i like, (nsfw included), but in time, it is just not a good idea, because firefox itself tend to get slow having to sort out so many bookmarks (i now have over 5500).
So what i started doing is, NOT use regular bookmarks for every single page i want to save. Instead, i started to use online bookmarking services, namely Diigo and Delicious.
In that way, you can save as many bookmarks as you want, and keep them apart of your "real" bookmarks, that is, pages that you actually visit frequently and want to have them quickly available. For any other page you want to save, a nice youtube video, an interesting article, a kinky nsfw link, a DIY website, a good joke, youo name it, it is beter (IMHO) to save them outside firefox.
The aditional perk is that you can the retrieve ANY of those pages from any other machine, and any other browser. just loging into your account, even share them, marking links as private (so only you can acces them via your account) or public, as a "social bookmarks" service.
Plus, that way you never have to worry if your firefox installation (or bookmarks file) goes corrupted, or if suddently you lose acces to your work machine and somebody else could mess up with your local bookmarks.
In fact, i will start to simply delete many of my bookmarks from firefox because they now live in the cloud, and locally save things that really matter.
Of course, Xmarks is perfect for syncing among firefox installations, and in fact, i also have a Home and a Work profile, but i've realized that over time, that just doesn't work.
And needless to say, but always make local backups of your bookmarks in every machine, and save them elsewere, (eg. just export them in firefox to a file and email it to you).
The bottom line, use online bookmark services. You can tag, sort, group, share, search everyhing, and you will not be dependend of a single browser or a single add on.
Tell me if it works for you!
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