Yes the keys are flimsy in the psr 740 too. That is one of the reason (among some others) why i chose to buy the 740 instead of the 2000. Unfortunately, I am used to the xp60 keys, which offer much higher threshold for digging in. Fortunately, though i am keeping my xp60 and whenever i have to dig in, i just midi to the 740, and play it through the xp60, where the keys don't make those irritating squeaky mechanical sounds, like the key is about to split in half if you hit it another time a little too hard.
In the shop you don't hear these kinds of noises because of all the other surrounding interference. Fortunately, though, I was able to get a rare quiet time with the psr2k, and noticed its mechanical squeaks, similar to the psr740, and decided there and then, as far as key plastic/springs quality is concerned yamaha is still being stingy. Although the 2k pitch and mod wheels are much better than teh 740.
Its surprising that the psr 740 and 2k which are made in japan are having the same quality keys as the psr160 which is a much lower model and made in malaysia.
Nevertheless, I am using the psr740 as much as i can, so that if there is a weak key on the keyboard it breaks before the warranty runs out.
Another thing i noticed is that the plastic used for the psr keys is very low quality. It is very thin, and feels like th stuff they use to make bath tumblers for third world countries. Compared to the xp60 keys, the psr's have a long way to go.
Why I chose to buy the psr 740 over the psr 2k?
1.Did they increase the quality of the keys? NO
2.Did they increase the quality of the vocal harmonizer? NO
3.Did they increase the quality of the sounds? Only 4megs worth, NOt worth it for me, since I have the xp60 which has 8megs built in, and space for more.
4.Did they put in a better interface? Yes, but now its too busy, with so many buttons. Plus the screen reminds me of my ancient Toshiba 286 laptop, makes me feel like I am supposed to have a mouse to navigate it. Furthermore, I felt it detracts from the music. I like my screens ugly/stoic like the xp60, keeps me centered on the music rather than twiddling my fingers to see which function I might experiment with next.
5.Any other significant improvement? Yes good sequencer, but my xp60 more than makes up for that, better sound editing, again xp60 sound editing covers.
6.I would have bought the psr1000 if they had put 64 voices, instead of the 32.
7.For home use, the psr740 coupled with the xp60 is a great choice. I don’t know about pro use. The pros have their own good reasons.

P.S. Be careful, when I heard one of my psr160 keys squeaking, I didn't give it much thought, and then a couple of weeks later the spring was shot and now the key just hangs.