ADA is well worth the $ difference compared to Dennerle.
You actually do not want an inert sediment, you want a sediment that does some work! Adds nutrients for plants so if you forget to dose, the sediment acts as a back up.
Sediments can act as primary source for nutrients, many locations in nature are this way. Other locations have rich water column nutrients and the plants do well there also.
But with rich sediments, you do not have to much labor or monitoring, testing.
That makes management much easier over time.
ADA is nice, but there are several DIY approaches to soil for CO2 enriched aquariums. Using high tech equipment is nice if you can afford it, many cannot. So it's nice to be able to use both methods and brand names, but also compare them to DIY and soils I might collect where aquatic plants grow well in natural systems(this latest newsletter, I do exactly that).
Dennerle is popular in Europe and use to compete with Dupla years ago. Dennerle marketed even more products, cure alls, remedies and heat cables where part of that marketing product line that Dupla had introduced and Dennerle copied. They do not sell Dennerle here in USA or in Asia. But I know of the various products and lines via the web from other folks who use their products.
It's better than living in parts of India where there's hardly any products sold of any sort/brand!
I've used cables for 10 years in the past, had them on 7 aquariums, made some from raw materials even(3 sets of heat cables), a simp test to see if they help/work etc, is simply to turn them off for a few months and observe plants/roots etc.
Then turn them back on for a few months, then off again, then on etc.
A few cycles of this will convince virtually anyone they offer no significant help.
There are no heat cables in natural systems where aquatic plants grow or wamrth from below, heat comes from above in most all cases for tropical plants.
Just like the sand at the beach when you walk on it.
I think heat cables work because people paid $ and where told they help, then they believe enough, maybe prayer? Then they might work.
None of the pictures of any of my own tanks have them/use them.
I used Dupla on 3 aquariums, and Sandpoint on one, then made my own from transformers and the correct wire gauge and a GFI ground fault. No one in the USA could find any significant effect from them even with the most skeptical close observations.
Hydor still sells them in this market, but they are much much cheaper, close to that of stick heater like Ebo Jager etc. Then aquarist are not out much $ if they buy them, and they do heat the aquarium.
I have never found that hurt any plants or an aquarium, just waste $ that was in your wallet, that is the worst thing they do, but this is the aquarium hobby!
It's all luxury items and a money pit anyhow