THE DESIGNERS VEIW: "Only low power single ended guitar amps exist, Fender Champ and Vox AC2 to name a couple.
At the end of the day, the ultimate judge of what is good sound is the player not the designer.
Therefore some people may prefer push pull outputs anyway (for different reasons) even with tubes which are just bias matched.
Then again, there may also be a completely unexplained and subjective reason why an amplifier without phase splitter sounds better to some people.
However, as an engineer, with some understanding (I hope) of what good guitar sound is, the following important factors influenced my decisions for the design of this range of amplifiers.
*In single ended output stages phase splitting is not necessary, the output tube - or tubes in parallel single ended (PSE) circuits - produce the whole signal. So there is no discrepancy in the harmonic content within the same signal.
In a two tube push pull output stage, such as two 6L6 50w amp, the signal is split in two parts, one tube produces the top part of the signal and the other the bottom one. This is called phase splitting. Ideally, bias matching the two tubes is not enough; signal balance matching is required too. This is because when they are being overdriven each one (tube) must produce the same type of harmonics at any given signal frequency. When chords are being played, various intermodulation (IM) products are being produced. If the two tubes are not full signal matched, the top part of the signal will produce slightly different harmonic products than the bottom one. Depending upon the players taste, this may deteriorate the sound at high volume levels. That’s why signal drive balanced matched pair tubes such as Groove Tubes are so very well sought after.
* Full class A - better sound continuity between low and high volume levels. For instance when you play a combination of heavy riffs and single string solos. No single ended stage could work in any other mode except full class