I flew last week from a club in the Netherlands and noticed a similar "go bag" for the aircraft. In addition, an up to date copy of the POH and W&B report was available in the office.
I too, purchase both a checklist (or create my own) and POH for the aircraft I fly. The FBO in the US I fly from keeps the POHs and W&B reports in the aircraft, together with the registratin and airworthiness documents (per FAA regulations). In the office, they keep a single piece of paper with all the W&Bs for the aircraft. This is quite useful, but I tend to double check these with the actual numbers in the aircraft "just in case".
One thing that concerns me a little about changing aicraft is that procedures do vary. For example, there are differences between fuel injected and non-fuel injected Cessna startup sequences. Similarly, V-speeds may vary.
BAL.