Nice work!
For the open lanes vs explore... I like the idea of exploring a lot, I play a lot of games for that, but I also like the tactical gameplay that lanes provide. Maybe a good hybrid is to have space lanes as man made objects, hyper accelerators either at end points, or like a highway, they dot the entire highway, either a series of poles or rings that make up a lane.
Have special rules for traveling in them, maybe you need special engines to enter and exit at will, else you can only enter at pre built points. Or have a device that can pull a passing ship out of the lane to engage in combat.
When flying in them you can have different combat scenarios, maybe some ships are better made for fights in the 'warp'.
The gates could have a maintenance cost associated with them, or, there could be some faction that builds and controls the gates (like battle tech commstar for their comms).
Either way, have the player or factions be able to build gates / lanes, at not a trivial cost to build and maintain. That way support would spring up along established highways and see increased traffic, but then you could still stock up on supplies and venture off the beaten path and maybe even establish your own travel lanes (or sell your charts to ai factions who might build routes to them).
Since that would let you have a huge world at one scale, you can also include some more eclectic exploration engines than do things sort of like 7 league boots style jumps or accelerate you to high speeds but give you little steering and things like that.
I alway thought that was the best way to handle jump points between sectors while still making you feel like its a big world out there. At the end of the day you want to speed up repetitive travel times and draw players and the ai into common areas, but you also want space to feel vast and empty at times too.