Was wondering what is the benefit from changing small bennett trim tabs to a set of k-planes? Better handing at higher speeds? Thanks

It kind of depends on the boat. Some boats don't really need tabs due to good design or dumb luck. For most boats though, one big benefit of properly mounted larger tabs is effectively lengthing the hull - by the length of the tabs. In big water, this can really come in handy. Generally speaking, size does matter here.

One big caution though. If you do go with longer tabs, make sure to do your homework before you screw them to the transom. Mount them incorrectly and you'll loose a ton of speed. Lots of posts here on how to mount them correctly.