I've only used Flourite, so I can only give an opinion on that. I have a low-light, low-tech 20 gallon tank.
I don't think it needs to be rinsed a ton, that might even be bad as I would think small roots need small particles. I cut both corners off the top of the bag and put it in my tub. I ran water into one corner and let it exit from the other hole for a few minutes. Sure it was cloudy when I added water and plants to the tank, but with a fishless cycle who cares? It all settled in a couple days and hasn't been cloudy since.
Despite all the list of ingredients, I don't think it dissolves and releases any nutrients to feed the plants. It does however hold on to nutrients well so you will need to add some fertilizers. There is conflicting information on the web on this, but I tried it both ways over the last year and no ferts was bad news.
I've been adding CO2 Booster as well, it has helped. With only a 20 gallon tank, commercially made stuff is fine for me and very easy, and it lasts for months. I guess I'm more lazy than cheap. Don't get me wrong though, I am very cheap.
Wouldn't you like to beside the seaside?