[mr_t]

Please take my reply with a grain of salt, it's subjective and not backed by any research.

Is it really the case that you lean slightly forward when walking forefoot strike? For me it's the opposite, my posture is way more upright in forefoot strike than it is in heel strike.

When I walk (or run) heelstrike, I usually put one leg forward and "fall" on that leg, which causes me to lean forward a bit.

When I walk (or run) forefoot strike, I do the opposite. I slide one leg backwards and thus push my whole body forward. My other leg lands directly under my body, I don't have to stick it out much to land on it, compared to heel strike.

Try to walk in heel strike very very slowly (like in slo-mo), maybe you'll feel that "falling" sensation and lean forward like I do. But it could also be that you walk slightly different than I do and don't experience the same.

Unfortunately I'm not aware of any research, but I also don't actively search for it.