No easy answer on this IMHO.
The system is about to change - albeit with backwards/forwards compatibility,
and there will be beacons with more enhanced features.
I think prices may fall even more as the amount of time before the new
generation stuff comes online diminishes.
If you need one - I wouldn't wait though.
I chatted with the CEO of Orolia Group (McMurdo/Kannard) last year, and the
impression I got was that they are leading the technology. They are investing
in and developing both the front end and back end of the whole system.
Having said that - personally I like the ACR products from an ergonomic stand point.
Sepcifically the Aquamate View - which gives you as much information displayed
on its LCD screen, as you could expect from the current system, short of any return messaging.
Its a 5 year batt life (6 from manufacture) and a bigger unit,
but I would prefer that - holding something too small in the water with cold hands and I think I would stand more of a chance of dropping it.
The smaller ACR unit also has a good "feel" to it - 5 year battery life (6 from manufacture) and is the one the RNLI chose.
I have the GME unit - again its a little larger than the McMurdo, and kindly replaced for free after Round Ireland.
If your going down to Southampton, try and handle all the current PLB models.
I dont think they are very different in performance.
Hope this helps