For outdoors I would go with the LW stuff. I believe it's generally preferred.
That said if you have a ton of standard suspension spares I'd probably run that just to save $$. Or if you are looking to fire sale some of those piece let me know
I called TamiyaUSA and tentatively the person told me the 4mm chassis was not drilled for the center MSX brace. He is looking into it and going to call back.
UPDATE:
Man fast customer service Tamiya has! They called back and said the finished product does have the hole drilled out for the center brace on the MSX. The pictures on the site were of a prototype.