That is an interesting question. Conrad's hosting operation is an extreme case, certainly. But consider two independently operated VPS relays in the same Digital Ocean data center, with arbitrarily similar IP addresses. And consider that both are vulnerable to compromise by Digital Ocean staff. Should they be part of the same family?
No, because Digital Ocean doesn't market itself as a relay hoster-- the percentage of relay-hosting clients wouldn't even near 0.1%.
On the other hand, if all (or the majority) of your operation contends on your customers hosting relays, I recommend they exist under the same family.