I've been toying around with the idea of setting aside money via my 401k specifically for use as a down payment on a house. To be clear, I do currently put 9% into my Roth 401k option and my employer matches this contribution, this is the maximum match that I can receive. My question is regarding contributing an additional amount on top of this contribution that I intend to use specifically for a down payment on a home at some point in the future. I live in MI, USA and am under the impression that you are allowed to withdraw up to 10 thousand dollars with little to no penalty for the purchase of your first house from your 401k.
The main benefit I hope to gain from this is convenience for myself, as the money would come out directly from my check and I won't have to worry about it until it's time to buy a house. There is also potential for slightly higher interest then a savings account, but that comes with potential for loss. I do have the option of putting the money into a separate 457k so I can keep my house money and retirement money separate easily enough.
So then, is there any massive disadvantage to placing extra money into a retirement account and planning to withdraw it at some point to aid in buying a house? And is there any benefit of using the 401k over the 457k to save for the down payment?