So its an opinion not a fact that the Tyros 4 doesn't have synthesis capability? Even Yamaha isn't foolish enough to claim that it does.

This isn't about my Wersi, I merely said the Wersi has synthesis capability, several types. Whether you think those synthesis engines are good or not is your opinion. Next to my vintage analogs the Wersi synth sounds very close. Not quite as dirty sounding as I'd like but very fat and warm. The advantage is of course being able to use various synth engines at one time and still having enough polyphony to play big chords

By the way.... I have an Abacus Duo Pro 25. The Abacus can be taken out by itself without the 76 note lower keyboard making it more portable. It weighs about as much as my Oasys did, maybe a few pounds more. If you're use to hauling around a plastic toy then the Abacus isn't for the faint or weak of heart.

As to cost... I have no idea what the current Abacus Pro version costs. I paid less for it than my Oasys, not much more than most people are paying for a Tyros 4.