The downside would be it takes about 3 to 4 business days to receive the rent money.

I think the biggest factor to determine which route to take is how much money do you have to start with and how much do you want your investments to be worth over some set period of time (i.e. 10 years, 20 years, etc).If you're starting with 100k and getting 10 to 12% return, you're making 10k to 12k a year?

My biggest problem these days are more (in some cases MANY more) people living in the apartment than are on the lease. 

What has been the biggest benefit and/or the greatest challenge?

I think the biggest obstacle is getting a lender that can work with you.

The biggest problem with abandoned properties are the heir laws.

Also, one of the biggest factors in looking at comparables is the finishes of the properties.

The HUGE downside is these homes all kindof need full renovations.

My female peers tell me that the biggest professional obstacle THEY face, believe it or not, is the wives.

Now I will admit the biggest mistake of my life was not keeping 50 or so more of the 500 or so I flipped, cost me millions.