In the end, it very much depends on your use case. CDNs make sense if you have many static assets and a very very high traffic website. Google published some study a while ago that people go away if your page takes more than 3 seconds to load. So, that's a good metric to work with.
What are the downsides of using surfer compared to say the same server without cloudron using nginx or apache
My instinct is to rephrase : what are the UPSIDES of using Surfer ....
But to answer the question, downside of Surfer is it does one thing serve files. Having a server with full range of facilities opens up possibilities (which you may not actually need/want) but significantly also carries management and maintenance. If 'set and forget' is what you prefer, then Cloudron and Surfer/LAMP is much better than having a traditional self-managed server.
And if the question was LAMP on Cloudron vs traditional server, then again the LAMP will almost all of what you would normally do on a normal server without the maintenance headache.
@jdaviescoates Add Hostinger to the list too. I signed up for a basic web hosting plan with them. I created a secondary user account in their admin panel for my developer so he could have access and it didn't work. I contacted support and it took them weeks to get it sorted. Meanwhile, I ended up sharing my main account credentials. I was asked identical questions by different staff (under the same ticket) and I was tossed around like a beach ball in a techno festival. I had better experiences with EIG owned hosts and those guys absolutely s***.
@qwinter I used to segregate apps on different VPS. Largely through fear of apps conflicting with each other (different modules/scripts) and my personal ignorance of how containers worked.
It all cost me a fortune !! Multiple small bottom tier VPS, each of which did not consume their resources to an adequate level.
I've since gone with steadily bigger beefier machines, and certainly get better price/performance, adding on extra apps to research ("play") and they don't tax the power of a well-spec'ed host.
I do have separate VPS, one for Cloudron, one for non-Cloudron Docker deployments, etc. So I do segregate apps to different hosts but hopefully with more logic than I did before.
So I would go with the best host which makes sense to you, rather than multiple smaller ones, except where there is a clear technical reason (e.g. I don't risk my main Cloudron host with non-Cloudron docker apps).