I am using Treepuncher to host my Tekkit server. I asked TP about the RAM allocation and was told they allocate 70MB per user slot. I asked about this being a rather small memory allocation based on the common statement that Tekkit needs 1 GB or better and was told they have no complaints from the users. To be honest, my 5 slot server does run reasonably well, service and support has been acceptable and I did re-up my subscription.
BUT
Am now looking for a different host.....thier 5 slot server just doesn't have enough memory to run a Tekkit server. Their support personnel are worthless, their only solution is to start a new world when its obvious the server is starved for memory. Instead of telling me that i needed to buy more slots they kepp saying the world is corrupt start a new one.