I figure having a M-1 Drive is nearly pointless for ships designed to land on a planet, but fine for ships that never land on a planetary surface. Anything less than M-2 and the number of planets that you can land on becomes a lot more limited. I dislike lifters because local gravity doesn't matter. Lifters negate local gravity. Period. Doesn't matter if the local gravity is 0.1G or 10G, your lifters work the same. That makes no sense. If that were actually true, then I can make "lifters" that will give Me 10Gs of thrust on a 1G world.
Personally I see 'lifters' starting out as:
1} limited to a small percentage of the shielded mass,
2} up to a maximum effect of x kgs of mass negated,
3} requiring high power per negated kg.
All of these improve as the TL of the lifter rises.
For extra-crunch give some lifters an inverse of third (or higher) -power-of-distance relationship with the local gravity field, or a 'ground effect' where they are more effective -- so we can build 'hover bikes' without having supersonic stratosphere racers.
Early lifters evenly cover the entire lower surface of the (spherical) shielded region; higher TL allows the lifter to generate non-spherical regions, to be evenly distributed over a smaller percentage of the bottom surface, to be placed at the center of mass instead of evenly distributed, or be located at any arbitrary point inside the shielded region with no need of emitters on the bottom surface.
Inertial dampers independently improve by TL in similar ways; maximum capacity, maximum off-normal angle, etc.
Going this route, a Man-1 Trader could possibly visit a 1-G world -- but the performance of the lifters might limit what can be safely delivered or lifted to orbit.
well sort of.