A-Class neighborhoods are high-end, desirable, with low vacancy rates.

I can't even count how many times I have seen posts on Biggerpockets from struggling investors trying to rent out Section 8 properties or D class properties out of state.Everyday there is a new post from a Newbie Investor who put their hard earned cash into a dud of an investment and cannot figure out why they can't find a solid tenant, why their tenants don't pay, or some other horror story related to investing out of state/D class real estate. 

I would like to have an active earning real estate job so that I can fund buying rental properties.

If you collect all the money on January 1st, you earn one month of rent in January, one month in February, etc.

Let’s say he puts 25% down (150k) and parks the remaining 50k “emergency” in HYSA earning a few percent net of tax on traditional.Just take (450k * 6.5%) - (50k * 3%) and compare it to 400k * 8.5% (scenario AIO). 

Yes, this is in Florida.This property is located in a desirable area in Florida.

I also think that paying off mortgages with earned income is not the best idea - it is a massive sacrifice over a long time that barely moves the needle.

You could invest passively by being a private lender (earning high interest), being a money partner (getting equity and a return for no work), investing in a syndication deal (similar to money partner but on bigger deals where you are one of many investors), buying another investment property and hiring a property management company, or investing in stocks. 

These ordinances make clear the state does not desire any jurisdiction from removing safe unpermitted units. 

Even in the “gentrified” neighborhoods of Federal Hill, Fells Point, Canton, Harbor East, desirability can be very block by block so you have to be careful that you understand these neighborhoods (and blocks within) somewhat intimately.