Yes, the Genos has newer, better sounding samples over the T5, but also contains all the samples of the T5 as well.
This means, removing DSP's and the Genos' 32 bit DAC from the equation, older styles (and midis) will sound exactly the same on the Genos because they're still using the old voices...
the reverse is not true, though! Until you go in, and actually utilize the newer, better voices; on both midis and styles, switching to the new drums (esp the Revo ones) produces an immediately noticeable difference.
There exceptions, however: the previous pre Tyros era kb's used styles dependent on an older drum sample library which no longer exists in the post Tyros era (with the exception of 1 of those kits being in the PSR340 retro download pack) and remapping styles from those keyboards (PSR8000, 9000, 740, 640, CVP209, CVP109, PSR2000/2100) onto the post Tyros era keyboards, the beats will sound significantly 'weaker' and thinner. (the old drums were fat and heavy, but also a lower resolution, and very, very short samples. Think Roland TD6 or from the late 90's or Alesis drum machine from the 80's if you don't have access to the retro drum). PJD actually put an audio clip up of what those old drums sounded like.
That is the one situation where putting the old styles on the newer keyboards sounds worse, particularly on the T1/PSR3000/CVP309 era instruments.
Mark