Combined speakers yeild even better performance

The other day I decided to try something I've always wanted to try. I wanted to see what it would sound like if I added an Energy Veritas 2.2 (good quality bookshelf 3-way speaker) to each of my Thiel 2.3 front speakers. The Energy speakers are stacked on top of the Thiels (using spikes with protective disks underneath) and are slightly angled down toward the listening position using longer spikes in the rear.

The results were very surprising. The dynamic range was improved, and the over-all sound was more coherent and full. The performance was incredibly engaging for both music and movies.

The problem is, I'm stuck in a moral dilemma. How can a mess with the design of such a great speaker as the Thiel, even if the sound produced is better than before?

I'm wondering if anyone else has ever tried this experiment.
"Stacked" speakers, usually of the same model, is an idea with a long and favorable history. Apart from lowering the power level at which the speakers opearate, you have taken one step towards a "line array". Screen speakers derive much of their good sound from line array configuration.

Regarding the "moral dilemma", say five hail Marys, light three candles, pour yourself a drink, and enjoy the music.
This type of thing almost never works out to the good. You will almost always end up with a lower level of performance than using one pair of good speakers. Firstly the sensitivity of the two speakers is never the same, secondly you are messing up the dispersion patterns of both speakers. Also the frequency response of the combined speakers is pretty much guaranteed to be much more uneven than a single pair. You ARE screwing up Jim Thiel's extensive design work on this speaker. Although your initial reaction is positive I think you will find that in actuality the sound from the Thiel's alone is really the more accurate reproduction of music
Infinitebaffle, hence my moral dilemma with messing with Jims hard work. I swear I would never do this unless I heard a noticeable difference (I love the 2.3's). And you may be right, what I tend to like right now, might change as I continue to listen. All the problems you mention are exactly what I expected to hear when I tried this little experiment (so imagine my surprise). About the only problem I'm hearing is that on some recordings the highs seem a little bit too brassy, but the Thiels were a little bit like that already. I have always chalked that attribute up to revealing what was on a recording to begin with. At least this is something I can change back later if I decide this isn't as good as I thought.
You may improve the treble performance if you invert the top pair so that the tweeters are closer together.

Just a thought.
Sometimes this can be something magical. In the late 70's I had done this with a pair of Infinity 1001A and a pair of AR 92. For some reason the sound of these two speakers together was incredible. They just filled the room with loud clear music. The bad news is nothing lasts forever, and I have never found another two that had the magic. Hey, We can play around with the toys any way we want, it's all part of fun of this hobby.