@Jim Fox,
I have a heavily planted tank that has been running with a Fluval Stratum substrate for 4 years. I had to move it 4 months ago, and as a result needed to add a new layer of Stratum to this established tank without uprooting the crypt/Eleocharis carpet. I carefully siphoned out as much of the stirred-up mulm layer as possible, then poured the new Stratum on top, cup by cup, with the water in the tank, disturbing the old substrate as little as possible. The crypts died back from being moved, but they are now starting to re-grow, as you see. It was a mess, but the roots lived at least. I don’t see why you couldn’t pour a layer of Fluval Stratum right on top of your existing gravel, if you don’t mind a slightly deeper substrate. Certainly, your plants will love it.
Also, Jim, I saw that you keep your tank at 79 degrees, but I didn’t see where you said what fish you are keeping. If they are discus, or German blue rams, or something else that really requires heat, then you have to run hot. But if you have regular community fish, they and your plants will do very well at 73 or 74. In my experience, plants prefer it cooler, and most community tank fish also live longer in cooler water. Just a thought for you.