I think it'll be ok, I'm considering dividing the 80g fuge into compartments and putting in a 30" section with a sandbed, this should help buffer the pH..I'll still have 150lb or so of LR scattered between the 3 tanks.... With this setup I have 180g of available volume, but will probably use something like 120g as the fuge water level will be much lower.
The other 40g I may divide into 2 sections with a foam divider and make 2 dedicated species tanks. I'm leaning towards a seahorse tank and a Mantis tank. Like I mentioned earlier, I'm going thru another "Change" and leaning towards smaller tanks and more of them, but the problem with a bunch of smallers tanks are water changes and water quality due to lower volume, I figure with all these tanks and the fuge centrally plumbed, I'll be able to enjoy the tanks without all the trouble.