Even simple extras like local guidebooks or maps can make a big difference.

Investors at this time should be extra careful

It 12 years, assuming you make no extra payments, you'll have a paid off condo that cash flows a lot better. 

Is it worth to invest and learn from their program in order to start my co-hosing STR side business just to get some extra money monthly?

Some companies might charge extra for maintenance coordination or inspections.

Shouldn't be any extra taxes involved.

For example: the multifamily sponsors will usually pay the considerable extra cost required to do a cost segregation analysis and this will increase the investor depreciation in the early years (versus an individual, direct investor who often will skip doing this because of the cost).The advantage of the passive investment is that you don't do any work.

It shows you are serious and willing to go the extra miles to make it work.

For example, this can be adding square footage, adding an extra unit, or adding a pool in a STR market/luxury market.  

15 - 20 year hold time.The rental investment calculators show that the four $300k properties would have a lot more equity in the future and many times the cash flow after a few years, but does the extra maintenance, management time and expense, etc. outweigh the numbers?