Try pellets.. if hes eating food off the top it would a good opportunity to start introduceing them. stick with high quality ones like NLS, or Omega one. i found omega to be easier on them at first since the pellet is softer. look for pellets with "whole fish" in them. my cuban and lngs all where much quicker converts then my florida. not to say they dont get feeders... because they do. but it makes the pocket book easier and feeder runs less frequent. imo there is nothing wrong with feeding yoy gar pellets ect as long as they have food available 24/7 so feeding pellets along with haveing the live available at all times is a great way to feed.
crickets are fine to feed but are proteon dense and fat lean. your gar need both, thankfully feeders tend to be the opposite and are fat dense and protein lean. in the end offering a varied diet is ideal, so as long as the crickets are healthy, and well fed. i would avoid the commercially available cricket feeds ect, and use a slice of apple or potate to gut load them, and fish food ( ideally pellets you would feed your gar). im not aware that the commercially available cricket feeds are good or bad for your fish... but its much cheaper and safer to offer pellets and a slice of veg/fruit for water instead.