Aside from the friends limit, most of your friends get deleted when your premium ends (if you don't renew it) and then you gotta add them all one by one again.
A better way to add friends to the VIP list wouldn't be so bad, if that's even possible.
Since 2010 default max. values are 20 for free accounts and 100 for premium. It is documented on website.
We will increase the cap for free to 25 and, dunno what player here needs more than 100 VIPs on a single account.
We will also add later the option via premium shop to leave the max VIPs increased permanently on your account.