VPS requirements

I'm finalising my plans for a new forum. I've decided on Xenforo but now I'm belly aching about server requirements.

In this thread http://xenforo.com/community/threads/looking-for-vps-recommendations.28737/ (I've not bought a license yet so can't post there) a few folks make recomendations. Nimbushosting and Xtrahost get a good mention. I've been on shared with EUKhost and moved away because of a support failure so am ruling them out. I've been through a long list made a shortlist and then gone searching for reviews. All of the larger UK hosting companies that offer VPS (with unlimited or high transfer allowance) seem to have given poor support to people who are only too happy to post reviews of their tales of woe.

Both nimbushosting and Xtrahost have specific bandwidth transfer numbers but I don't have a clue what I'm going to need so I don't know if these are restrictive or generous.

Would anyone be able to let me know their bandwidth transfer usage vs membership, posting numbers etc. Perhaps then I can make a decision with my eyes open and get on with launching my site.

Many thanks