Unfortunately we do not have an experience with HubSpot.
We are planning to have marketing automation features though, most probably by the end of the year. It will really go beyond the SEO.
JP, I imagine your question here isn't relevant any longer, but I"ll give it a shot in case others want to know.
At Aptera we use both. Some of the main missing ingredients in Sitefinity that Hubspot has are:
Social Media Publishing
Reporting based on users(once landing pages filled out)
We view them as complimentary products although we see some overlap. We also built integrations to allow us to use Hubspot elements on Sitefinity pages. This is particularly useful in conjunction with Sitefinity's personalization options.