Against our agent’s recommendation, we saw those as big ticket opportunities for price reduction.

This was the same math done when you purchased the triplex, if you purchased it as an owner occ and used the rental income to help qualify.3) If you want a rational reason why non-owner occ math is more generous than owner occ, consider that non owner occupants have to put big fat down payments down, and have more skin in the game generally. 4) Rental income (anything about it) is frequently overlayed. 

There also has been a dramatic reduction in the number of bidding wars (https://themortgagereports.com/47875/home-bidding-wars-down).  

If you're planning on purchasing investment properties in 2024 with financing, my advice is not to wait for potential future interest rate reductions.

I think I will offer her a 3-year lease with a slight rent reduction.

Oh, and to your question on why principle reduction is not considered in my analysis... you can't eat equity.

If they accept my offer, I know I'm making a fat check, and that is why I make it a point of telling sellers I have ZERO contingencies.

It sat on the market for 43 days and had to do two price reductions and closed at $1,085,000. https://www.redfin.com/CA/Los-Angeles/23711-Ladril...I'm going to be all in around $950k ($250,000 out of pocket) when you factor in closing costs when I bought it.

The upper unit has pretty much been gutted (there is still some flooring left but studs otherwise), and I was wondering if it is worth doing any sort of noise reduction with the upper unit to possibly avoid future issues between tenants. 

This is dangerous because the seller has an incentive to minimize expenses in order to make the investment look as attractive as possible in order to get it sold; the real estate agent stands to earn a fat commission check.