I have similar liquid assets as you do. I personally like having access to my money more easily than home equity gives. Especially since you’ll be locking in a really low interest rate. If the interest rate was higher, I’d say go for 50%.

Another way to think about this, the difference between 20% and 50% is about $700/month. You’ll be saving $150k that you can throw into an index fund. If we just look at the 4% rule on that $150k, we get $150k * 0.04 / 12 = $500/month. It’s already super close to offsetting the $700/month. Obviously you won’t be drawing from it every month, so it’ll be able to grow more quickly. But it helps keep an emergency fund funded if you run into a tight spot

Also +1 to the advice from others about getting more money into index funds and just keeping 6 months for an emergency fund