Down payment on an investment property.........or max out Roth 403b and 457?

[Beck H.]

Hello all!

I am sitting on enough money to buy an investment property in the next year or so.  But I just started a job that offers a Roth 403b option AND a Roth 457.  As I understand it, I can max out each one for a total of about 45k next year (and as much as I can put in for the rest of this year).  

So I'm starting to think that maybe I should have my paychecks fund these accounts for the next bit of time, and then use my downpayment money to fund my life (i.e. my paychecks may be like $300 each month after money being sent to the retirement accounts).  Then when my downpayment money runs out, go back to receiving normal paychecks and have like 60k in Roth accounts that I can transfer to my personal Roth when/if I separate service, and I can buy any stocks, dividends, trade options, and never get taxed (unless the government changes things).

I am still trying to run some numbers, and it's a tough idea to wrap my head around, so I thought I would ask y'all.  Don't roast me if I'm totally missing some basic reasons why this is a bad idea!