So I went ahead and bought a Zipato RGBW bulb (Bulb2) online to replace the Osram RGBW one, and received it in the mail today, but found three pretty big issues.
Issue 1. When it is screwed in all the way the light will not come on (This is US bulb and in the US) so it will only work if I loosen the bulb until it nearly falls out. Has anyone else had this issue?
Issue 2. Smartthings lists this as an Aeon LED Bulb which is obviously wrong, but works to some extent. The generic Z-wave RGBW handler seems to work fine with limited options. I also tried an Advanced Zipato RGB handler but this never wanted to work at all. Even so, with the basic Z-Wave handler the bulb would turn on and I could change color.
Issue 3. (MAIN ISSUE) For some reason I cannot get the Smartthings Smart Light app to turn on the bulb or change color. I have used this app for a long time with the Osram Lightify RGBW bulbs and that generally works well, but with this bulb absolutely nothing. It will not turn on the light, it will not change color, it will not do anything. Strangely Alexa will happily turn on the light and change color, but I bought this to use with Smart Lights.
So if you have any experience with the Zipato Z-wave Plus ‘Bulb2’ (RGBW) and the issues above, ideally with a solution to resolve them, please let me know.