The cost reduction certainly matters when you are seeing 2 cards a turn.
This card is clearly better than staff of Nim, but that’s not saying a whole lot. Staff hasn’t been playable in a while, and even when it was it was fringe.
I think 6 mana is just too much in this format to play the card. Especially for a card that doesn’t outright win the game if you don’t respond to it. Drawing multiple cards a turn is worse for agro decks than it is for any other deck style in vintage. The only thing you are looking for is more threats. While this does pump your board (a 6 mana non-creature chief of the foundry) or stop a planewalker (6 mana phyrexian revoker), it still will take at least 2 turns to impact the board (remember shops plays around 26 mana sources) by replacing itself with a new threat. That’s the math on it, and the math isn’t good for a 6 mana spell.
Compare it to Wurmcoil (a card I think is overplayed and pretty awful in shops), at least if that card isn’t responded to, it wins the game by itself. This card only makes you draw more cards, it’s pretty meh.