Alex, the SP1mk1 which you have was a development and improvement on both the BC1 AND BC2, as the need was to retain the midrange clarity of the "1" yet with the power handling of the "2." This yours do in spades and, unlike mine, the SP1 will compare properly with ANY modern speaker of quality and IMO will give very little away.
I don't think I mentioned this, but when I spent some very enjoyable hours in great company and audio gear, I was able to listen to some £800 Rega speakers, a three way I believe, and I thought they sounded wonderful. All that gave me cause for concern was a remaining touch of spit-n-sparkle in the treble, which a typical vinyl source would largely mask in any case. In all the FE parameters of pr@t and tunes, these were excellent. What appealed to me was that the timbres of acoustic instruments were good as well, making for an endearing package way beyond the now totally outclassed ELA's of old - IMO...
I can't go on and I can't go back, I don't feel so matter of fact,
I tried and tried to make good sense, What's the good to try it all again?