I've upgraded from shared hosting to managed SQL, on top of regular, shared hosting.
I had started this blog on google's blogspot in 2007 and migrated to this domain in June 2010. The blog now has 3500+ posts and over 1500 visitors per day (often touching on a regular basis, as – for instance – today, over 2000). But there are also around 20 subdomains that get a fair bit of traffic, for a total of around 3000 visitors each day.
Just using shared hosting, at around 4 to 5 dollars a month, is no longer an option. Things had become really bad and it was almost impossible to publish/ update posts. I was constantly getting 404 and 500 error messages. Also, its weaknesses were too easy to exploit, and this blog was constantly being hacked, including by political hackers.
Moving to managed SQL guarantees memory for my 20+ SQL databases. This option is going to cost a bit (exact amount to be determined after one week's experimentation) but the speed has already dramatically increased. I've never seen the blog (at the dashboard level) as responsive it has become now, after upgrading the SQL server.
Greater capacity also means I can install more defences (plugins) against hackers.
With my blogs now earning $100+ (AUD) per month, I'm not going to be out of pocket. I guess everything has a cost. Cheap hosting has its limits.
Let me know if you experience any improvement in speed.