Other than that I can't see any other disadvantage if comparing to a C class Multifamily due to maybe a higher turnover rate.   

The biggest disadvantages of a HELOC is it could get frozen if the housing market goes down and home values drop, and it carries a variable interest rate which can go up at any time. 

I also only offer MTM leases, which was never been a liability or disadvantage to onboarding quality tenants.

Are there any hidden costs or disadvantages?

One thing to be cautious of is if all the other rentals in the area have water/sewer included in the rent, you'll be at a competitive disadvantage by trying to charge for it.As far as lawn and snow, first talk to your PM.

Can someone please help me decide where to file my LLC, I'm a bit unsure the advantages and disadvantages.

I know I would be able to sell this property within weeks without this deal.There was language in the one party listing that was really disadvantageous to me (unrepresented) as a seller.   

The 2000 mile away option does have some baked in disadvantages.

When would claiming it ever be a disadvantage?

Or at this point, should I really put all of my focus on a single strategy (likely BRRRR).I think there are advantages and disadvantages to both, so curious to hear from people who have gone down this path before.Thanks.