I vote for premium themes for important blogs, and the reason is security.
FREE THEMES - may no more be up to date, and therefore load slow and even have security vulnerability.
I use them for simple, quick blogs that I am not too much worried about, if something really happens to them. There are many beautiful and feature rich free themes, so for variety reasons I like to use them. But would not recommend them for your really main important blogs.
Remember that free themes often have no further updates by their developers. So, a theme that meanwhile got 2-3 years old on your blog
- Might have become vulnerable with its old coding.
- Maybe it loads slower then an updated theme would.
- And mosti importantly, hackers are constantly looking for back doors, and this is also why WordPress gets constantly updated. What about outdated codes on old themes?? Ever thought about? That may be a wide open door for hackers
- And often times you have no clue, if potentially a theme even was created with a hacking back door in mind by purpose, and given away for free by purpose.
I do not want to paint too much of a horror scenario, but when it comes to a serious business blog, vulnerability and stability issues must be excluded.
PREMIUM THEMES - Support, ongoing maintainance and updates mean more security, and stability
For an important blog, that would make you lose money or even business, if they would break, I think only a PREMIUM THEME can do the job. A premium theme
- Has more stable codes, because you paid for a product that must work properly
- Technical updates and maintainence is a continuous process, and as customer you always get updates automatically
- Developers take care of possible vulnerability issues, because possible leakages get proactively fixed. Which in a free theme hardly anyone does.
- When you pay for a theme, the source is trusted, unlike a free theme that you get from anonymouse...
So, my vote is FOR PREMIUM THEMES because of security and stability reasons.
P.S.: Just found this very detailed article on the topic - HOW DANGEROUS USING FREE THEMES CAN BE: