I agree 100%. I did a ball valve mod at first and then the gate. Much better with the gate (obviously), it's impossible to be that precise with a ball valve. A ball valve ends up being more trouble than its worth but the gate really makes it a better skimmer. Easily worth the $19, he!! it's worth $40 honestly.
The recirc and feed go together, you can't do one without the other. How well they work depends on how efficient your feed is. The Recirc will greatly increase contact time but the feed leaves room for great variation in skimmate production. Suppose your use a small powerhead to feed your skimmer and you place the power head on the bottom of your sump. While that is the WORST thing you could do, it will still draw water from the same place that your skimmer did pre-mod. So your skimmer will draw the water from the same place, in more or less the same amount but with greater contact time. Now if you were to gravity feed your skimmer, you'd be feeding it just the slime from the top of your tank right into your skimmer which of course is the most protein laden water in your system. Now if you add greater contact time to more efficient water collection, you've got a good skimmer.
I'm personally not a fan at all of non recirculating needle wheels, I just don't think they are efficient. It doesn't matter how big a pump you put on them they still don't have access to the tools available. We use overflows to skim the slime off the surface of our tanks. Being that we all have a tool that collects the most protein laden water in our systems, why not use it? Why dump that highly concentrated muck into a vat of water, mix it up and then have a skimmer try and clean it? It doesn't make sense.