Essentially, you're now not only trusting 1 entity but 6 - if any of those 6 will log / leak data, you're offering them 1/6th of your traffic. The probability of that happening is significantly larger than using only a single provider (if you want to calculate it, there's the Binomial Distribution).
That being said, if any of those providers would then leak your traffic patterns, all the attacker would get is your VPN IP address and not your home IP address. So essentially, you're making it even harder to correlate DNS queries to you.
