This thing is pretty neat but it does have some down sides as cubfan135 has already talked about in his video and comments.

1. it does not store the items like you want. If you have 4 minecarts with chest in the system and you place a stack of cobble to be put into the system it will not place the cobble in just one minecraft. In fact I have noticed it will place the cobble in the chest minecarts randomly so some my have only 1 item others my receive more.

2. Minecart have been known to disappear.

3.It cost a lot of iron to upgrade. For the average player this will be a problem but for some such as my self we make iron farms fairly early in the game so this will work for us.