I hate Device Diversity in gaming arena... but there are reasons to eat the bait

Being a fan of Guitar Hero since its first release on PS2, I thought that everything would be wonderful in PS3 in what regards to music band simulation. Then came Guitar Hero III and the wonderful Rock Band. But Rock Band did not come with the same flavour to Europe: no pack with the BD and the instruments, which had to be bought separately and individually. That means much over twice the price in the USA even accepting a 1€=$1 conversion.

And hell has been raised even hotter and wilder taking into account the lack of compatibility between the peripherals of both GH and RB worlds. A patch has been announced for Rock Band support of the GH3 guitar but I do not know if it is true. There is no news about Activision trying the same (well, no news further than Activision meaning to sue Harmonix for the patch).

Taking into account how much I hate that Sony does not standardize music peripherals and that I would like to pay once for a guitar or a drum set and be able to play both games, what is the reason that tempts me to acquire another music band simulator?

For example, an expansion like this :-)

[ADDED ON 2008-11-01] Gosh! You can also buy Motley Crue's classic album "Dr. Feelgood"... Aaargh!