They can sometimes rank better if you're on your own private IP versus a shared IP especially if you plan on cross-linking between them. However, that's going a bit off topic as there's more to it than just that...as for multiple hosts, I'd recommend it if you're serious about your website and can afford it. If it's just a small hobby site and it's not producing any money, then don't worry about it but do keep regular backups just in case.