This might not be financially feasible for you, but I would consider getting all your upgrades done at once. You are entering a very slippery slope. I'm talking about going with the Statement and SE upgrades. Considering the cost and risk of making multiple shipments, plus the time of not having your source, it makes sense to do it all one time. Many people usually end-up eventually getting all this done. If you can't afford it, then go for the Reference upgrade.
Rob
Rob