Sorry about late response...was offline for a couple of days.
Don't have experience with fluval edge...most of composite substrates have to be rinsed in a bucket like forever :( and they don't last any longer, and most of time a lot less, than your dirt tanks ...ok, what I have had to come to turns with is this: do I want this tank to be a self-sustaining ecosystem (or close to it)...or do I want high-tech lighting and co2?
I have done both and for most part, I like my little ecosystems better. But I am still fidgeting around with low-tech setup, trying to get everything working how I want it to...and let's face it, at this point in my life, I cannot afford $5000 or more for 1 tank setup in high-tech...which is what your looking at to compete with the "true aquascaping" breed out there!
So, someday I want to aquascape a huge aquarium, but I am still learning about the plants and how they behave underwater...so, for now, I will perfect my ecosystems and maybe make a hybrid someday soon...so many options...;)
You will never be happy with your tanks if you keep up an internal debate between high and low-tech, so choose one or the other, or hybrid of the two, and don't look back after you begin.
MTS: like any snail, they can be a pest and breed like crazy...but, they are the only choice to help you aerate your soil under sand cap to keep out pockets of dead anaerobic soil....you can poke holes with a pencil/stick/fork to help, but I don't know how effective that is. With MTS, I just leave soil/substrate alone because I know between snails and plant roots, my soil is taken care of adequately. I know they sell them on aquabid and I have plenty available if you just want to pay shipping.
...yes, you might have to, on occasion, dispatch some extras (or you could attempt to sell them on aquabid ...or give them away...;)
OldFishLady states emphatically that your "ecosystem" needs snails to work, to be an ecosystem. I will defer to her experience...even if pond snails love munching on aquatic plants and even with my Brown ramshorns that seem to eat my plants when they say ramshorns don't eat your plants (huh...could have fooled me!). Seriously though, at least my MTS don't eat my plants!