I thought I would report back.
I am very happy with the Ceros. It’s comfortable enough to use for four hours plus with minimal hand fatigue and the dust extraction (even with a domestic vac) is fantastic (with regular bag changes…). Especially noticeable on the odd occasion when I forgot to turn the vac on and wondered why it suddenly seemed to be snowing. I used a dust mask (anyway) and ear plugs, the latter particularly to block out noise from the vac.
The 60 Grit HD disks turned out to be a bit of a problem: very aggressive, but also poor extraction and they seem to generate a lot of heat = lots of pilling, which in turn resulted in swirls and more heating etc. Probably better for timber surfaces.
I ended up getting through a lot of 80 grit Abranet disks, having decided that it made more sense to keep the rate of surface removal up (using sharp abrasives) than trying to persist with dull disks. I found that interface pads that got pilled could be restored with a soak in cellulose thinner and a scrub with a toothbursh.
I followed up with 120 grit, and that seemed quite smooth enough.
I used Toupret fine surface filler for finer imperfections and found it very easy to use. Memories of Polyfilla horrors and obviously filled screw holes now in the dim and distant past.
The final pre-painting result on the walls was absolutely stunning - virtually a polished finish. Seemed a shame to have to paint, and definitely exposed the limitations of my wall painting abilities. I imagine that only a sprayed finish could really do justice.
I used the Mirka hand-held hand sander for architraves and the like, and for areas where a more gentle touch was required, including filled areas on the walls and pre final coat on skirtings. My impression was that the initially aggressive removal of the Abranet abrasives with the hand sander very quickly dulled, although the abrasives remained sharp when used without being attached to the hand sander (e.g. just using an interface pad for strongly curved surfaces). In other words, the abrasive qualities remained, but needed more (fingertip) pressure than was possible with the hand sanding block.
For the painting I used:
Wooster Alpha brushes: liked these (1 and 2") very much, especially the 1" on architraves. I also tried a 2" Corona Cody, which I found too heavy.
Wooster pro-Dooz roller sleeves - maybe not perfect enough given the virtually flawless substrate?
Mythic All-purpose primer: very easy to achieve a lovely flat finish, albeit very thin and not very opaque, and I ended up doing multiple coats.
Little Greene Absolute Matt (Shirting - same for all LG paints) for the ceiling - beautiful soft finish.
Little Greene Intelligent Matt for the walls, applied with 9" Wooster Pro-Dooz rollers: needed three coats for a fully opaque finish, and I found it very difficult to achieve a perfect finish (despite following all of the advice on this site and Jack Puhl). The fact it is a very tall hallway, which is lit from a very acute angle (fanlight over the front door or recessed ceiling lights), meant both that I couldn’t complete ceiling to floor rolls (too high for a short-handled roller; too narrow for a long handled roller) and then any imprefections are ruthlessly exposed by the side lighting. I took the advice about rolling right to the edges with a 4.5" pro-Dooz roller, with excellent results (effectively zero brush marks visible in cutting in).
Little Green Intelligent Eggshell for skirtings/ architraves. I used ‘XIM latex extender’, but probably not enough so still got brush marks, especially on the larger areas of skirting (although I’m no fan of a factory sprayed look). Maybe I’m missing something, but I can’t work out why I should pay top top whack for ‘premium’ paint and then have to add antifreeze (or whatever) to it, in order to achieve a good finish, and on reflection that probably held me back from adding enough XIM. I am surprised at the level of plasticky surface sheen of the finish, especially when viewed at a very acute angle (we have stairs up from our kitchen to hall, so you end up with hall skirtings at eye level).
3m 2090 masking tape, which took some of my nice matt wall paint with it (Grr), leaving me with some remedial work. But no bleeding at all.
I’ve learnt a lot from TP and am grateful that you have been willing to share your knowledge. My decorating abilities have leapt forwards, definitely helped by having the right kit. Other than involving a lot of time and effort, my only real problem is that it makes the rest of the house look distinctly scruffy…