As one of the hardware engineers I guess this is a question for my table. In the manual we state that recommended max ambient temperature is 35 degC and not exposed to direct sunlight. This is the blanket recommendation to allow for reasonable variation in other environmental conditions like ventilation, other machines close by and such. This does not mean that the unit automatically self destruct in higher temperatures, nor that it turns itself off. There is an internal temp sensor to ensure good tuning and other analog stability (there is also additional slots so you can get the calibration perfect for your ambient temperature).
I trust the user to take care of the machine, it’s built to be used and somewhat abused, but to care for it. If the ambient temp for some time goes above 35 degC that is utterly extremely unlikely to cause any damage. The thing is also that we can’t say how hot it would need to be to actually be directly critical for the unit, in the case of a live set in a sauna (like above 70 degC) you will likely start noticing crackles in the digital audio because the heat throws off the signal timing, but it is likely that it still doesn’t die…immediately. (We have tested this, but simulated the sauna). But for how long would it stay a healthy machine at these temperatures? To be honest I have no clue so I can’t recommend this. What I can recommend is to use it at max that temperature that still satisfies the recommended temp of the internal components (for those more into electronics you know that there is a difference between recommended and abs max, and we design everything to be at below recommended temperature to be conservative). Then we arrive at 35 degC as a reasonable temperature with good marginal.
So, sorry for a long-winded answer, but it’s a fairly complex question so I want to share a bit of the reasoning regarding the ambient temperature. It’s build to last long and be a stable companion under the operating conditions we recommend, even if it is more complex than just an absolute temperature number