Sent you an email Mark, sorry was having some much needed beauty sleep
I do recommend the LS27 for a listen if considering purchasing a 2nd-hand Ref-3.
Key aspects such as noise and other similar sound related performance are better with the LS27 and for some this can be critical.
For more subjective sound quality/preferences it will be closer, but anyone listening should ensure they choose the gain setting on the LS27 that matches their preference as they are subtly different (myself I preferred it in low gain setting).
The Ref-5 is subjectively better, but diminishing returns really do kick in when comparing the two IMO.