(Potential) First Time Home Buyer - Expert advice needed!

[Jen W.]

Hello! Bigger Pockets newbie here. My husband and I have been extended an opportunity by family friends to either rent or purchase their home in Coeur d'Alene ID. We've been running the numbers but thought we'd share with this community to get a fresh perspective and hopefully hear a few angles we haven't thought of.

3,500 Sq Ft Home. 4 Beds, 3 Baths. Estimate market value today ~$1.4M

- Rent Option: $4,000 per month

- Buy Option: $1.3M. We would be required to place a down payment of $500K and then they would extend to us seller financing on the remaining $800k with a loan of 5% interest only. Our intent is to stay there 5-10 years. When we sell we would pay off the remainder of the loan owed. 

Other helpful numbers: Home insurance ~$1000 per year. Prop Taxes ~$4,000 per year.

What would you do? Thoughts?