After that, you’ll want to investigate commercial financing which is entirely different (mainly in a good way at this point) but I wouldn’t recommend starting out with a Corp/ commercial as the drawbacks likely outweigh the benefits until you’ve maxed out personally.

Exchanges are great for tons of reasons, but they aren't a cure all and they come with some drawbacks.  1031 rules limit what you can buy, when you can buy, how much you should spend, how you treat the replacement asset, etc. 

The draw back to these loans is that they are more paperwork heavy than the other "portfolio" types of loans....but if you have ever received a loan on your primary home, it's likely that you will go through the same type of paperwork here with conventional lending.

Are there any drawbacks? 

The draw back to these loans is that they are more paperwork heavy than the other "portfolio" types of loans....but if you have ever received a loan on your primary home, it's likely that you will go through the same type of paperwork here with conventional lending.

Labor is a big drawback... quality contractors tend to either be busy and booked or expensive (or both).

Drawback is you can only choose from 2 or 3 finishes. 

Having a (very nice) kitchenette instead of a full kitchen is admittedly a drawback, although I'll basically only be missing a range. 

Is that an advantage or drawback? 

There are two main drawbacks when it comes to Class C.The first one is that these properties require more maintenance and repairs than Class A and Class B, but this problem should be eliminated for 2 out of the 3 units that you are considering buying.