Rademaker, Charlie, the Compact 7 (with Radial technology material introduced in 1995 and improved a little bit last year) is NOT an LS3/5a equivalent or replacement. It's about 8 times the size, I think.
Harbeth made an LS3/5a replacement in the same shoebox size. It was the Hl-P3 and was (arguably) better than any 3/5a in a couple of respects. I have a pair, and I think they play just a little louder, are not nasal like the 3/5a, have a clearer less colored midrange and more tuneful bass. But they were replaced in 1996 or so by the HL-P3ES, same size but somewhat different I understand, which Harbeth now markets as the 3/5a for the next century (millenium?). Spendor sells something called the S3/5 I think that Ive heard is also better than the 3/5a in some respects.
But, I dont think any of these comments are responsive to the original question. Which 3/5a is better? The early Rogers are classics and now command high resale prices as they have quite a following. If you believe the December 1993 review of the P3, new Harbeth 3/5a and comparison to a ca 1978 Rogers, there may be something to be said for the later model Harbeth. StoneAudio in the UK may have a few left of the last production run.
There are about 50,000 LS3/5a afficionados out there. One of them should endeavor to answer Rademaker's question.