Avoiding to become "House Rich, Cash Poor"?

My spouse and I are looking to buy our first home in Belgium and are trying to determine the best way to approach the down payment and mortgage. I want to get the best property we can ... but without biting off more than we can chew in mortgage payments or becoming "house rich, cash poor". Curious for your advice!

Here is the our current plan:

• Cash: 150.000 euro
• Mortgage: 250.000 euro

Cash -- We have been able to save up quite a bit over the years, and have each received some money from our families. One of us has a higher total net worth, but the other now has a much higher income and the net worth will catch up soon ... so we're planning to go in 50/50. Combined, that down payment of 150.000 euro would represent approximately 40% of our joint net worth. (Is that a good amount? Too much?)

Mortgage -- It looks like we would be able to get a 250.000 euro mortgage at a ~3% interest rate from a local bank. Our monthly payments would be around 1400 euro/month, or ~20% of our joint monthly income. (This is similar to what we are spending now on rent.) That way, even if we are wrapping up a lot of money in the house, there should be wiggle room each month to cover unexpected expenses.

Is this a good approach? Is there something we're forgetting?