I do have a free tier, but it is for a different segment (hobbyists), and no "conversions" from free to paid are expected. In a way, I maintain it as a hobby and a service to the community, also hoping for some PR and visibility.
In general, I would strongly discourage a free tier in B2B SaaS. Nothing that has value is free. If you need to offer something for free to "lure in" customers, then I'd say your main offering does not provide enough value. Also, you will be "luring in" customers who expect and want free stuff, this is not the kind of customer you want.
Do not get caught in the race to the bottom with your pricing. Do not listen to pricing advice on HN: people here are not your customers. Many expect B2B SaaS to offer $19/month plans, which is impossible. In my opinion, any B2B SaaS with an ARPU lower than $50/month is doomed to fail. If you find a counter-example, it will be a company burning through VC money to get "user growth", or a loss leader from a big corporation. Think about it this way: at $19/month you are looking at $228/year revenue from a customer. Ignoring all other costs, if you spend ONE HOUR PER YEAR supporting that customer, you are already losing money.
Build something that provides real value to businesses, price your service fairly, err on the high side, and see what happens.
Trying without having to commit is important, but that's what free trials are for. I had free trials with a credit card required for the first few years, because I was afraid of the support load. Then I switched to free trials with no credit card required and in retrospect I should have gone with that from the beginning, since the niche I'm operating in is fairly small and most of my customers are smart engineers, so support load wasn't an issue.