On reflection, it was FT uploaded to MH (not Ancestry as I don't think this was part of the free deal). After some months fiddling with the basics on MH, they offered me a year's subscription less 50% which I considered worthwhile as they had started the labelling system. I also colour-code families on my Ancestry database.
If I take an MH test which they are currently offering at £39, would I perhaps get a slightly different range of matching cousins down the scale or are they more likely to remain unchanged?
Your old FTDNA v1 test would have been a very close match to the old MyHeritage v1 test (I think FTDNA actually did the testing for them), so that kit would very closely match older MyHeritage or FTDNA kits uploaded to MH. However MH changed to GSA as did FTDNA to GSA in 2019, so you might gain some different matches. HOWEVER. I am pretty sure MH uses imputation, and some of the matching is dubious as a result - I think someone, comparing their matches to their parents', estimated that matches below about 23cM, a 1/3 were false matches, and matches with small segments, say below 15cM were also very unreliable.
https://isogg.org/wiki/Autosomal_SNP_comparison_chartIf you could tell what kind of kit you were matching on MH, it would be useful, but unlike GEDMATCH, there is no way to tell that.