These are all very valid points, gentlemen.
Some time ago, I resigned myself to the conclusion that there is NO single sound decoder out there that can qualify as the "holy grail" of sound decoders. Presently, for MY tastes, Loksound has satisfied nearly every criteria for what I would consider an "ideal" decoder.
As Richard points out, the speaker is a major part of the equation. The Loksound Select that I installed in the roomy PA-1 is married to a hi bass speaker in a nice sized enclosure that takes up about 20% of the carbody. Lovely sound indeed! By contrast, the aforementioned C-620 installation by Bowser has a single mini oval speaker— maybe .625 x 1— in a very shallow enclosure. Obviously a compromise that must be considered.
I remember the first Tsunami heavy steam decoder that I installed in an N&W P2K Y-3- (what? 6 or 7 years ago?) and I was immediately blown away at the quality of the sound eminating from that engine!
So I was expecting the same for the Tsunami Diesel, even more so considering the long delays to production, but I was more than moderately disappointed when it did finally appear.
You're spot-on about the top speeds of some engines, Richard. I was hoping Walthers would speed up the most recent release of the RDCs but, alas, no. Best I can get is about 50 MPH (they were geared for 85.) Their newest gearing of E-7s & 8s is pitiful as well. All my old Life-Like stock will scorch the ballast
I had considered purchasing the Kato P42 so that's why I was checking them out at MB Klein. The sound ones were released later since, I guess, an outfit named Kobo was doing the installs. Seems to me that they started out with about 20 of each sound model and it looked like the Tsunami's were moving a bit quicker... just an observation.
Maybe the OP will chime in here and let us know what his specific concerns are?
Happy Railroading! Ed