There are pro's and cons to a central filtration system as far as I can see it to me issues with it were, running all tanks on the same water means you cant have fish with different water types in the system, it can be complicated to setup, and the main reason which has caused problems with people I know who have these setups is disease. It wont take much just that female you've been looking for ages for for a lone male that you just cant wait to add and boom all your fish are sick and it takes alot of med's to treat the whole system. Also even if you qtine all fish somethings show no sign's (worms) and you tie up alot of fish. Also I have thought that with overflows alot of baby fish would struggle not to get washed down them?
For all the reasons above (and the fact my fishroom is a dogs breakfast of random sized/shaped tanks stacked all around the place) I have gone for a heated room and individual filters, will be trying to find a kick ass airpump and go for all air filters at some stage, but these aren't cheap..
I am sure that central filtration systems are awesome when running well and if you do it or not depends on how you feel about all the potential problems.