From decades ago at LTN, in B732 (Cat 2 a/c) days, there was no CAT 2 RW26 at LTN. This was due to the terrain in the undershoot. The RA readout was not suitable and at 100' ATHR the RAD ALT was unreliable. CAT 3 was allowed because the a/c was at 50' above the flat (almost) tarmac.
To solve this problem I think they installed RAD ALT reflectors on the approach lights so the readout at 100' ATHR would be accurate. However, approaching the DH point below 1000' (3nm) the RAD ALT readout will be sensible; it will then change from a reducing RA height to a rapidly increasing RA height as you fly over the valley. The RA height will then start to reduce again at an unusual fast rate and can be very confusing.
Seeing this 608'DH = 100ATHR might suggest another solution has been used to the radar reflectors on the approach lights. Perhaps there is now better land surveying of the undershoot. The locals might tell us the uptodate situation. But, most modern a/c that are CAT 2 are usually CAT 3. So they would fly CAT 3 in dodgy weather, if available. There are technical reasons, both airborne & ground equipment, that only CAT is available.
What might be interesting (and I can't remember what we did in B767 days) is the 500' ALERT HT. This is a RA height and a decision about the Land Status. 500' height = 1.5nm on finals. I wonder what the RA readout is at this point? Locals again?