I've gone through the National Roll of Honour, plus the Aden Veterans' site roll of honour and one published in a 50th anniversary magazine for the same organisation; the Radfan campaign, is, of course, covered under their auspices. There are slight differences - I've taken the National one as definitive, using the others for service numbers which can be searched.
The following emerges:
1. No soldiers died at the end of Jan 64.
2. There are no deaths in February or March which might be men dying of their wounds
3. There is one death in April (Cpl Malcolm Davies, R Signals), where the circumstances of the death aren't easy to find online (not least as some sources put his death as May rather than the official record of 3 April) but the casualty is buried in what's now Yemen. Evidence from a death in October 64 suggests that repatriation to the UK of serious casualties took place, which makes me think that a two month gap between this death and the evacuation makes it less likely that this was one of the soldiers evacuated, although not impossible.
4. Only one death in May 64, Lance Corporal Wakefield of the RAOC, cannot be immediately attributed to an incident on the day of his death.
5. In June, Lt Handfield-Jones, RE was killed amd laid to rest in the Silent Valley cemetery. Again, one suspects that this is not related to the January incident.
6. Sapper David Asquith died in July, and again, the circumstances of his death have so far eluded an online search.
7. There are no deaths in August or September which could relate to the January evacuation.
8. There is one death in October, Bombardier Chapman, where the circumstances surrounding his death - like Lt Handfield -Jones and Spr Asquith - cannot easily be located searching online. S/Sgt Bourne died in the UK of wounds sustained earlier in the year.
9. From November & December, only Driver Smith (RASC) and Cpl Slater (R Sigs) could possibly fit (I've not had the chance to search for more detail yet, and shan't until tomorrow, I fear).
This is an imperfect piece of research. But it's a start. I would suggest that the evidence so far means that there is an high probability that if the four soliders were British (rather than Aden Protectorate Levies/ the FRA), the rescue effort saw them survive 1964 at the very least. Further research (the old fashioned way, using books) may allow the removal of some or all of the above names who might have died later as a result of injuries, and if anyone gets to Kew (which doesn't open until Tuesday), then the records from the hospital are likely to give the answer in due course. But for Tuesday, I'd say that the chances are that the evacuation did save those recovered, and certainly ensured that they lived for some time afterwards.