End of March 2011 I had the wonderful opportunity to Visit Andi from Gainphile blogspot. I auditioned his S16, S15, and the Pluto clone.
One thing was clear already upfront with all of Andi's speakers: The value is extremely good for the money. One has to consider that many things in Australia are very expensive compared to Europe and the US, although speaker drivers cost some money in Europe as well.
My observations of how the speakers sound, are pretty much in line with what Andi describes himself. So I will only report additional observations or with a different emphasis.

We started with the...
S15 Econowave:
Good bass and good highs, although not the softest and smoothest in the world. During the time of the visit I could not find a clear preference regarding the foam plug for the compression driver (i.e. with or without it).
If you can speak of weaknesses at all with this speaker then I'd say the mid range was not quite (very subtle) in line with the rest. But that is certainly a matter of the Eminence Beta.
What really didn't work for me personally, was the auditory scene that this type of speaker produces, regardless of the nice looking polar response. And this was clear within the first 10 seconds of unbiased listening to the speaker. It is like looking and hearing through a pretty sharp rectangular window that sits in some distance between listener and speaker. Crossing the speakers in front of the listener changed and smeared the representation a bit but did not remedy the impression altogether. Actually for a few minutes the crossing even sounded somehow confusing and unnatural until the brain adapted (we started with this setup).
So my long standing plans to build something with a bigger waveguide are on ice for an undetermined period of time. But thanks for refreshing the experience, Andi ! This proves to me once more that constant directivity alone is not enough. It only demonstrates its full potential and beauty if it goes hand in hand with wide dispersion (in regular small rooms).
We did not test the SPL capabilities of this speaker but I’m convinced it can go really loud.

S16:
At that time it used the same compression driver as the S15 in a different WG accompanied with a backfire tweeter. I liked this WG/driver combination much more. In a split second the room was full with music and I could take a nice bath in it. Tonality, timbre etc. all really good. The tweeters felt a little bit like as if somebody would aim a laser pointer at you, more direct than a conventional dome; clear. Crossing their rays in front of the listener worked better for me than with S15.
So in total, this is a very pleasing speaker ! With the WG, the stage has only a notch less depth than Aristoteles. However, the integration of mids and highs was not 100% "smooth". But a regular consumer would never have noticed it as it was very subtle. We both conclude that it has most likely to do with the backfire tweeter, which is off set to the compression driver and has some pretty wide radiation within its operating range.
Anyway, for me it is a clear winner over the S15.

Pluto clone:
Apparently as everybody else listening to that speaker, I had to walk up to it after the first few chords. Little bastard :-) Andi has equalized it down to 30Hz, yikes ! The little mid woofer was working quite hard and thus preventing it from a real loud listening level but it certainly has a fun effect and we had a good laugh. As expected, it really takes a long walk into the direction of any of the pipes until the sound collapses into the closer one.

In my opinion, Andi clearly achieved his goals: Life-like reproduction with cost well under control (to use my own words). This proves, that the polar response (in combination with the room) is the main actor on the scene.
It was a great day and a superb experience at Andi's and I enjoyed it a lot !