You have 20% available in cash, I would say use cash, and let the money in the roth continue to grow.
The $10,000 first-time-home-buyer thing is a 'lifetime limit' from an IRA/RothIRA toward a home purchase - such as a down payment.
The money taken out would be tax free *IF* held for over 5 years. It's taken out in this order:
1) annual contributions, 2) conversions, 3) earnings.
And as DrFunk says, the IRS rules define 'first time home buyer' as someone who hasn't owned a home in 2 years. So, if you ever want to use the Roth for a down payment in the future, you would sell your home, move into an apartment for 2+ years, THEN buy as a 'first time home buyer'.