Ask HN: does pay per use pricing method works?

I'm tired of seeing the same pricing systems on every startup it comes out: plans. I understand they are designed well and is common in the industry at this time but I think we can improve more. Some pricing plans are well distributed but some others, not. They just list a bunch of stupid features just to fill up the list and become something important to show.

I am developing a SaSS system and I want to implement a different approach for pricing. It starts with $10 for everyone, but you need to pay extra when you need to use or do other stuff.

Let's say you're 37signals Basecamp and, one feature is SMS alert. You either can pay the pro account extra 200 a year or instead you pay those SMS you need to send that x month for that x project you're working on. If it becomes a must feature, you pay a fee and you have it for default in your account. If not, you pay per use.

I've researched a lot for my project and I found people doesn't need all the features all the time. Most of the features I've been researching to put on the system are, more used occasionally than usually. I want to charge for the occasional use and, if it becomes a must, you can pay it too instead paying for something you will never use.

Has anyone tried this system and can share results? I don't know the side effects of this in real world projects. The only effect i tested with people told me that plans makes things attractive because "it has that and that just in case i need it to use" and that's all.