Good idea, Master. I would like to see a comparison. Side by side. Is this TTTF?
I am sure the 30,000 sqft per hour figure is a bit exaggerated. You could probably have one guy apply the fert and one guy apply the slit seed. 5000 sqft in 30 minutes. If you criss cross a bit with the fert and seeder...it wouldn't matter.
Compare the 5 pound seeding rate with 10 pounds--not all of it will take hold.
Convince the customer it is better--as a slit seeder is used for seeding not aeration--puts the seed into the soil--does a better job. So you can charge more.
Also allow the customer to choose--good seed or at extra cost--best seed.