All bills paid - include in rent or charge separately

[Jeremy Michiels]

New to investing and am assessing a 4-plex. It currently cash flows well, but includes all utilities in the existing leases. As I seek more revenue opportunities, I'm curious if it is better to leave as is or migrate billing separately for water and utilities based on some allocation formula after I receive the actual bills. 

My question is...In your experience is it better to include utilities in the rent payment or line-item these out for each tenant?

Any other things to watch out for in "all bills paid" properties?

Longer term I will investigate splitting the meters to offload this entirely.

Thank you in advance.