Don't rule out Robert Doornbos ( he was quicker than David Coulthard in the Red Bull car
).
It's hard to say really... Sutil for instance.. I was not impressed with him while he drove for Germany in season 1, but everybody still sees him as a bigger talent than, say, Nelson Piquet jr.
Likewise: Premat or Lapierre were never even considdered for F1 eventhough they dominated season 1.
As for giving a go: I'd say let Jeroen B have a go... he may not be the fastest in raw speed, but he's consistant and makes very vew errors. He has a decent finishing record if you ask me
(his only DNF of his own fault is Beijing 2006)