I've had both Scanspeak and Hiquaphon and I prefer the Hiquaphon, they're smoother more sweet and less harsh.... And almost twice the price.
https://willys-hifi.com/products/hiquphon-ow1-92-tweeter
£286 for a matched pair.
If you're used to Scanspeak I would stick with them, Gerry at Falcon Acoustics will be very helpful.
https://www.falconacoustics.co.uk/drive-units-1/linn-isobarik-replacement-drive-units.html
They're under £70 each, so less than half the price of the Hiquaphon. But IMHO not as good. Falcon may give you a deal on 4 units so even cheaper.
I'm absolutely sure my hearing isn't good enough to pick out 0.5 dB difference in a pair of tweeters.... But the Hiquaphon matched pairs promise this level of sameness.
When I replaced all 4 of mine a couple of years ago it was like having new speakers, they sounded much better, more sparkle and a real delight to listen to.
I don't think the crossover cares which of these two types are fitted. The screws are a direct fit and may have some thin plastic washers so keep those safe. You'll need a good beefy soldering iron, a hot glue gun and some neutral clear silicone.
https://www.toolstation.com/dow-cor...xiikCQ_NQ2pjAouOe0DaK-OlybvBM3XgaAiXCEALw_wcB
Make sure the fit is air tight particularly at the screws if the washers are not there...a dab of silicone will do the job. This worked for me. You'll have most of the silicone as spare.... I used that to stick down some loose paving slabs in the garden.
I have some pictures of my replacement adventure, let me know if you would like to see them.