Holding onto a HELOC long term is painful, so you'll want to make sure your exit from the HELOC is planned out. 

I think 1 commercial loan is way more pain than 1 sfr, but 10 commercial loans is way EASIER than 10 SFR. 

Capex and tenant issues tend to exceed cash flow and when you decide to exit after a couple of painful years, you are in for another surprise:It is shockingly hard to sell cheap homes! 

Also, any advice for avoiding those unexpected surprises (or at least making them less painful) would be super appreciated.

In fact, September is nicknamed septi-hambre in Mexico, which means the month of hunger or famine because it's the worst month of the year in terms of tourism in Mexico.

What pain points or problems have you encountered or seen when evaluating real estate deals?

I paid PMI which feels painful but if you keep your eye on the long term prize it's worth it. 

You can Google it, but in general Judicial=Longer, more painful foreclosure process.  

The time it takes for the draws from tenants and then the ACH transfer to you leaves you getting pain on the 7th or 8th of the month, the $1 ACH transfer fee is an annoyance that has drawn some complaints that are as petty as the fee feels, the new tenant application features are sub-par, and I'm not sure how well it properly informs tenants of the additional charge for credit cards as I got panicked texts about the added fee from a tenant already going through some hardship.

I know lease prep is a pain, been working on them and there are lots of new regulations and it would be easy to screw it up.