OK, every V8, does not matter if 512MB or 2GB has 3 touch screen buttons at the bottom of the outer screen, which can be seen as 3 dark squares when the phone is turned off and tilted against the light, as mentioned earlier.
These 3 touch screen buttons can be used on every V8 (512MB & 2GB) with the music player, when the flip is closed.
Reply-to-text-messages feature with those touch buttons is only supported in the 80.56.xx firmwares, now this means that no 512MB V8 can use them as 80.56.xx is 2GB V8 firmware, but Linuxmod3, 3a, 3b and 4 for 512MB V8 have this feature as I used 2 of those 80.56.xx CG's in those Linuxmod firmwares for the 512MB V8.
Only the newest Luxury Edition V8 have this reply-to-text-messages feature as they have the new 80.56.xx firmware, but most Luxury Editions do not have this as their firmware is 80.54.60 or older. So, in a way the 512MB V8 with linuxmod3b is more advanced then most of the Luxury Edition V8's.
Just having this 80.56.xx firmware on your V8 does not automatically gives you that reply-to-text-messages feature as it depends on the existance of templates, which are used as the reply text, those templates only exist for english, german, traditional and simplified chinese and any other language (e.g. italian, french etc) will not have this reply-to-text-messages feature simply because there are no templates in that language. Luckely you can create your own templates on the V8 in your language and as soon as you have done that and you use a 80.56.xx firmware the reply-to-text-messages feature is enabled and working.
I hope this will sort out any misunderstanding and/or confusion about what does what.
I'm really glad that Rasputin spoke up on this finally. I don't understand how there could be so much confusion about something like this. I also don't understand why this guy needs to be told so many times that the phone does have the 3 button touchscreen option. It's like he refuses to believe his phone is broken and won't stop until someone says "You win, we're lying, the buttons don't exist"