Hi crystal sluka - your concerns are valid ! I myself was in your shoes, I've been using D7 for close to 10yrs. Things were great at one point. I am not even going to mention the money I spent on D7. But I should also admit that some of the vendors I purchased D7 Mods from all of sudden vanished & they were nowhere to be found. As result when D7 gets upgraded to a new version, my site started going south because some these Mods need to get updated as well. Long story short, It was very painful to keep Dolphin current because I was using too many Mods which needed periodic updates and I got tired of babysitting the site. In today's new technology, companies are embracing the new trend where Apps & Databases are becoming more & more self-managed and self-upgraded which enables companies to focus on the main core of the business rather than babysitting the underline infrastructure. In the Cloud world, they call it Serverless.
Having said that, I made the decision to migrate 2 of my D7 sites to UNA about 3 months ago. The learning curve has been a bit challenging, but I really have nothing to complain about so far. The fact that UNA has the option to self-update & self-upgrade itself to keep the site current is a HUGE PLUS for me, not to mention the site performs well and very RESPONSIVE which is another cool feature that can save me money w/o the need to deploy Portal App for my site. Also the support is not bad, I see everyone on this Forum helping each other including UNA team.
What I would like to see though is to have a HOW-TO indexed wiki page so new people like you and myself can go there & find things quickly to get a jump-start. I know you can do a search on this forum, but having an indexed Wiki based on categories would be more effective which will help the community find things quickly and avoids asking redundant questions that have already been asked by someone else. I understand this is a fairly new platform, I am sure UNA team have few things planned out to help the community and to make this great platform successful.
In short, in the long-term, things will balance out & we should see the money savings as well, and not to mention now we have less headaches to worry about as far as maintaining the site is concerned. 
Cheers.