The problem with walk behind slit seeders is that they don't have a roller on the back to press the seed into the slits the way a 3 point slit seeder does, so for good results the area should really be rolled to achieve the necessary seed to soil contact. Also, most of the lower priced slit seeders Ive seen drop the seed out front before the slits are even made so who knows if seed even ends up in the slits. For most cases, I prefer cores over slits.
MDA no. 29204 (3-C)(6)