The A400 should just about drive them ok, it was a decent enough amp. We have an old Audiolab 8000a we use occasionally as part of our test set-up and it manages with them - the more power the better though! That said our main amp is only an 80-odd watt Naim Supernait and this drives all our models well, power supply and current delivery are more crucial than watts.
Spec-wise they're pretty much the same as the originals - I'd say sensitivity is around 84-85dB realistically. The only changes from the original were the tweeter, which was no longer available so the best replacement we could find was used, very close to the original - the cab MDF is slightly different as it's from another supplier too but this is more a case of slight changes to character rather than spec. The sound is on the lean n' mean side which means they time very well and convey the musical message as it should be done, some may find them a little lightweight but, depending on your taste this may well be preferable to slow and bloated!
I'm not sure how performance figures/specs come about from most manufacturers but in most cases they're optimistic in my experience - even our own! I just checked the online literature from our site 88dB is way out, 8ohms impedance will be more like 6ohms, 200watt power handling is fine (this is still a vague figure as a 500watt amp would drive them better than a 200watt one and to be safe many think that this means you couldn't damage them with a 50watter... sigh...) and it's this sort of thing that confuses the public.
The close team we have in place nowadays do not like this randomness so all products from the last 2 or 3 years will have pretty accurate measurements, I'll probably introduce a maximum SPL rating for new models as this is more an indicator of how loud a speaker will go (along with sensitivity) than the wattage one is. Most competitor models we test are about 2-3db optimistic in their sensitivity ratings too - there are exceptions such as ATC (for example) who are honest about things though!
At the end of the day these figures are only a basic guide - most modern amps cope perfectly well with most modern speakers, it's not as big an issue as it used to be - the quality and character of the sound is far more important at the end of the day.