Jupiter 6 / Jupiter 8 / Prophet 5 comparisons?

How does the Jupiter 6 compare to the Jupiter 8 - am I right in
thinking that the JP6 is simply a six-voice version of the JP8 with
the addition of rudimentary MIDI?

And how do the Jupiters compare to the Prophet 5?

I have a P5 (rev.3) and love it although it's a temperamental little
monkey and I suspect, rather more limited in scope than the Jupiters.

Lastly, what price would one expect to pay for these at the moment
(I'm in the UK) - the JP8 seems to be very expensive on the rare
occasions that they're available (& looks gigantic), but I'm assuming
the JP6 & P5 are of comparable value.

Thanks,
MattF