When you get into higher purchase prices though (sticking with 3-4 units) you'll find that you don't need the rent to value ratio to be as good as you do with cheaper properties.Many of your expenses will not be proportional to the property value or even the rent rates.

Proportion of value on land vs real estate will need to be determined.

Rents are lower too, but not proportionally so. 

It will be important to understand what is standard in your market, you don't want to put yourself at a competitive disadvantage.You should expect property taxes to go in proportion to the amount of value you add.

Georgia, Hawaii, Michigan, Nevada and Washington are some of the states that have fared worse because of a high proportion of tourist or manufacturing jobs.

EMD proportional to the value of the House.

(Not talking about including expenses and selling costs and stuff)I'm thinking it would be transferred proportional to the original basis I had in the first property I 1031ed. 

.”-- Herman Melville"Let your heart feel for the afflictions and distress of everyone, and so let your hand give in proportion to your purse.” -- George Washington

I'm in compact mode.

Even with rents being proportionally higher than expenses today, I'd still use 40% as the lowest percentage likely to be incurred (and that's not considering either the problems of covid rent moratoria or the general increased difficulty of evictions or the greater activism surrounding renter protections, all of which raises costs and/or lowers income).