I'd say combine a new version of Scouts with Scientists. There's just so much potential overlap there. Get scouts away from the whole espionage thing, we've got spies for that, and back into actual exploration, surveying, experimenting and so on.
The "adventuring" scientist is probably more like Indiana Jones, getting out there and her hands dirty, as she conducts experiments or studies new phenomena or digs up ancient secrets. And who is she most likely to be hanging out with? Scouts.
The new core system would have to revolve around system generation (and what lies between systems) with a focus what interesting things, adventure spurring inspirations, there are to find there. Alien cultures, rough-and-ready diplomacy, strange artifacts, etc., etc. Less slide ruler and more action adventure. Yes, have details that sound technical to flesh out whatever form you have for documenting systems. Have hex-maps and systems for generating topography on the fly. Maybe borrow some of the old detailed sensor system (so players have fog of war to add some mystery) rules from MegaTraveller's World Builder's book.
Seems to me divorcing either scientist characters or scouts from a more detailed world and system building supplement doesn't make sense. Both are all about discovering the new and for a GM that means he needs to be handed the tools to make the new! And it had better lean towards the interesting and inspiring when the answers roll in.
I'd also maybe toss in an appendix for alternate lab rat scientist characters or a scientist themed campaign. One could use Ars Magica's focus on the covenant (lab) and research techniques in all their variety and time consuming nature as a template. The question is how do you handle science and invention? Or do you focus mainly on limited prototype improvements of existing technologies?