Hi plasma800,
Like you … I think highly of the people at Texas Mattress Makers and I have spent some time talking with the owner there (Youval) and he certainly tells it like it is and is what I call “mattress people”.
I completely agree with this and it’s why I often suggest that if all else seems to be equal that going with slightly firmer is usually a better choice than going with something slightly softer. The only effective way to make a mattress that is too soft any firmer is by removing and replacing the foam layers that have softened rather than adding a firmer layer on top which will just follow any soft spots or sagging in the layers underneath them.
Most importantly … congratulations on your new mattress … I think you made a great choice 
I’m looking forward to your feedback (and pictures would be great as well) when you’ve had the chance to sleep on it for a bit.
There’s really two answers to this.
One of them is here
The “alternative” version … for those with more conspiratorial leanings … is here
Phoenix