Help with Dynamic DNS

Hi,

Since I switched to GNU/Linux and freesoftware I wanted to host anything that I use with other providers like emails, webhosting, cloud storage and "SaaS" thing on my own computer.

So I tried to get a static ip address from my ISP for 30€/month (ouch!), everything was working great until I wanted to setup my own email server and had issues sending emails to others providers like (gmail,outlook etc...).

I found out what was the problem and contacted my ISP so they configure a Reverse DNS for my domain name, unfortunately they didn't know how to do it so I canceled my static ip address subscription and now I'm running my website and mail server with a web hosting provider.

Finally I found out that is possible to setup a dynamic DNS with a provider (no-ip.com $29.95/year).

I don't know what is the difference between this method (Dynamic DNS) and static ip with my ISP, is it worth it, any feedback on this, what about privacy?

Thanks.