It is going to feel pretty bad if the game reaches a point where you run out of counters, but tapping something down 4 times is often enough to get you there anyway This reminds me a lot of Jodahs Codex
This deck has everything you need for a competitive Commander deck, with brute force damage, plenty of card draw potential, some decent ramp and card cost reduction, as well as plenty of diversity amongst the creatures to always keep your opponents on their toes
Secondly a lot of the good lands to go and get with the Knight are way to narrow to ever have slots in the cube such as the Sejiri Steppe
Since the discard is optional, you have complete control over how aggressively you filter your hand
As for the main drawback of MDFCs (coming into play tapped), it is a concern, but not a huge one
Historically Sheldon handled many of these expenses out of pocket, resulting in a disruption with his passing