From the US Sailing database, the low/high/mean ratings for the Tartan 31 are 144/165/153 and for the Pearson 31-2 (the late 80's model) 150/177/159. Not all that significant.
FWIW, I owned a 1979 Pearson 32, and it was absolutely built like a tank. However, I think boats built 10 years later came from essentially a different company with the same name (and head designer). With boats of this age, you have to evaluate the condition of the particular boat(s) you are looking at, because after 25 years owner maintenance, or lack of, will have a huge effect.
Kloudie, you wouldn't be referring to Espirit de Vie? We spent the night at the Mandeville city dock weekend before last & had a great time.