To me, it seems like this is a pretty underutilized resource for SaaS companies. With group giveaways, you have the opportunity to create relationships with companies in your niche while exposing your product to a wider audience.
Specifically, you have the opportunity to expose your brand to an audience already interested in your niche. With a group giveaway, you can grow your email list or increase social media engagement. Email lists are especially powerful because you can upload that list into Facebook and retarget those users with ads. You'll have a conversion rate between those ads that target a cold audience and those that are retargeting users on your website.
So: Have you ever done a giveaway for your Saas? Why/Why not? Is it something that you've even considered?
Give a ways really don't work. Unless the give a way is something your target customer really needs, and the general population sees no value in it.
My guess would be that giveaways work much better with consumers, who are spending their own hard-earned money, where SaaS is usually B2B - spending is less emotional.