The reason we didn't call it a "free trial" is because you can still keep using the service after 30 days. Some SAAS products have free plans that have caps on the amount of data you can create. We're basically saying the cap of data for the free plan is whatever you create in the 30 days -- that could be hundreds or thousands of bookmarks. You'll still have access to everything you own after the period but more importantly, if you weren't satisfied with the service you can export it all anytime.
Actually, we do sync your bookmarks across every device you use. The Firefox plugin is available as both an addon from the Addons Center and XPI file for direct install.
Did you have any problems installing the plugin, or did you just have trouble finding the page that links to it?
That's gonna be a tough challenge but we've focused very much on building a solid product that looks and feels native and runs fast.
You're right there are many bookmarking apps and most of them are really good so we are taking a stab at a problem that's been solved many times before. ;)
There are also highly educated people that are losing jobs because what they do is so repetitive and can be done more efficiently with a robot or program.