Which LS3/5a?

You should also consider the Chartwell and Goodman's versions, along with KEF. 

Spendor made them too. FWIW Roger Modjeski owned the Chartwell version.

i prefer the higher impedance models of ls3/5a if memory serves correctly, it has been many years

that said, proac super tablettes out-perform the 3/5a in every important aspect...

it is what put stu tyler and proac on the map in the late 80's

There is a friend who goes by LS3/5a on another (SH) forum who has owned a number of these fabled models over the years who you could reach out to.

If I recall from a recent conversation, he is of the opinion that the bigger box offering from Falcon is the bee’s knees.

”Designed by Malcolm Jones and sold by Falcon for many years, the updated Q7 features the same Falcon B110 and T27 drive units as used in the Falcon LS3/5a in a specially extended LS3/5a-type cabinet to produce an optimum Q=0.7 system with extra bass compared to the LSA3/5a (+2dB @ 50 Hz).”