I may well be out-of date, but I think a new Kandid is £3800 and that you get £800 pm trade-in for a worn Kandid.
A Lyra Kleos I think costs £2900, but the trade-in value on a worn one is half that.
IIRC, Lyra made Linn-brand cartridges for years, including some absolute crackers, but not any more.
I compared Kleos to Krystal and preferred the former for SQ, though the general presentation/ voice is not too different. I had an Akiva many years ago and the Kleos reminds me of that, but with a bit more get-up-and-go.
A Krystal is only £1400, but I think you only get £250 back when you swap new for old.
According to the Linn price list on the Cymbiosis website, the price of a new Kandid is now £4,175 and it looks like Linn will offer £960 trade in for a Kandid to a Kandid.
Do we yet know what trade-in will be offered when swapping one Kendo for another?
If the Kendo costs £3000, it looks the natural competitor to the Kleos. However, if the net cost of a replacement in a few years were to be nearly £2500, then the long-term cost of using Kendos will be a lot higher than the long-term cost of using Kleoses.
Of course, that may not matter if someone significantly prefers the Kendo for SQ or if the preference is small but the use is low enough that a cartridge will last many years.
As far as I can tell from the price list that option does not appear to be available, but that might be because it’s a new cartridge. Probably best to consult your usual Linn retailer.
The XV-1s is a very heavy cartridge. I expect that your Ekos SE can probably cope, but your dealer should be able to confirm whether you need a heavier counterweight.
I can certainly vouch for the slightly less expensive, and lighter, Te Kaitora Rua, which I have in an ARO on my LP12. A truly great combination!
Really personal choice but the Linn one is current and authentic but the Harban ones no longer made are superb as long as they fit your decor.
In your system I’d have the black one.