They are all on one lease however I have an addendum that specifies what portion of the rent is due by which individuals on the lease.  

Each individual needs to be considered individually as a whole person, not just numbers.Just because somebody has some number points in a system somewhere does not automatically make them a good tenant, and that is really the only criteria I can post in my ad.

Each month the tenants pay me their individual portion of the shared total.

I would join forces to attain things that are out of reach to me individually.  

Property is individually metered for gas and electric, and i would be paying water.

Some lenders I know will do for less but the goal would be for you to raise rents on non-performing units, which there probably is.You can also buy the portfolio, fix up individual buildings then sell off the ones you don't want.

If you are harder working than the average individual, you are compensated directly for that. 

One thing to note when looking at the individual markets, you can make or loose money in any market.

Another thing is that I have individual insurance policies that cumulatively cost much more than the insurance policy for a single 4-plex.

And the purchases were made by the LLC rather than as an individual?