Well hopefully the first big change you'll see is, they stop sucking on your channel cats!
With a little more in their belly, I would'nt be suprised if you see them a bit more active, and a lot less agressive. Once they get used to a regular feeding cycle, they are not going to act like starved wolves untill it's zuchini time.
Fresh veggies seem to encourage more natural growth rates. You'll see lighter bands in their pattern as they start to have mini growth spurts.
Pleco Poo. The downside to having a pleco with a full belly is, he's gonna start decorating the tank with some truly amazing strands of poo. It's natural, it's normal, it's not healthy if they don't. Before you start thinking of him as a colon with fins, keep in mind some of your other catfish might consider this gunk edible, as it's still got nutrients in it.. yuch.
Color pattern. As they get bigger, and better fed, you should see more patterning in their hide. This is at least true for gibby and hypostomos.. I'm not sure which you have, both are considered common, and both are great fish.
Man I'm glad to hear they are taking zuchini at last Jag!