The reviewer, Ian, said on the video that he couldn't find any records of the trials involving the 1896 Schlagelmilch or any information on why it was rejected or not further developed.

It sure looks user friendly to field strip and to clean. If anyone had foreseen trench warfare of WW1 perhaps this would have been pursued?

Also it seems that Herr Mannlicher agreed with your assessment of the magaxine and trigger group removal. Watch tiis video at 04:49 : Mannlicher 1901/04 Carbine

Das is gut!