I'd actually recommend you phone around just to see what repair costs are to see if the saving is worth the lack of warranty;
20-25 years ago, replacing the key sensors on a clavinova or psr was in the $50 ballpark for labour, regardless of brand.
Without pointing fingers at specific brands, depending on the difficulty of "getting inside" to the rubber double or triple sensors? I've seen labour anywhere from $150 to $1500. No that's not a typo; some brands labour has gone up approximately 30x. (the parts have gone up as well, but some have barely gone up in price, some parts have skyrocketed) Your local situation is going to be different unless you live in Vancouver, but I'd find the closest local repair shop and call them for ballpark repairs.
What can go wrong? Snapping the adapter input (which is soldered in) which actually shatters the pcb is expensive (20 years ago was about a $250 repair including labour and parts, last one I saw was $750), motherboard dying (P&L used to be about $900, now closer to $1500, which is almost the cost of a PSRsx700), blown speakers (<$100 20 years ago, but now still only about $150), dead screen ($500 20 years ago, about $900 now)
Again, that's Vancouver. 20 years ago you could purchase a house for about $350k, now you'd pay that much for a parking spot. Average house in Vancouver was $1.5m in 2023 (down from the peak of 1.75m in 2016 & 2017). IN 2003 average price of a house was just under $400k.
That's if you only include Vancouver, Vancouver in your calculations. Once you include all the regions of the Greater Vancouver regional district (incl Richmond where I live) the increase staggering: 2003 average price across GVRD was $90k for a home (ie condo, townhouse, house). In 2023 that'it's now over $1.2m (yes that's including suburbs now), and average price of a *house* across GVRD is now $2m. (yes the districts outlying Vancouver have gone up even more than Vancouver itself).
The point? Non warranty repair costs have skyrocketed here, but then so has everything else.
Find out if the amount you're saving is worth the lack of warranty.
Yes Yamaha has the best warranties in the business. But all brands, all instruments, can fail (and from decades of personal experience, some specific instrument models fail more often than others, but nobody is immune).
Mark