Uncoupled ordering and payments systems are definitely a sign of a scam. Taking payment for pre-orders is also a sign of a scam. However, a company history of delivering actual innovative products is a big sign of a non-scam.
PreOrders are not a definitive sign of scam. We begun with just preorders, waiting time was close to 2 months for DC to setup servers.
Pre-orders in certain industries is quite normal infact.
Uncoupled ordering and payments is not a definitive sign of a scam, A LOT of companies still operate that way. Even some major companies.
I can name a few DCs off the bat which operate this way, one rather large even which doesn't even have online billing system customers could access!
While neither is a good thing, it's not definitive proof of scam.