Emery Davis wrote:

The real 'Bloodgood' is the best of them for keeping red in the shade.
Be aware that this is a large and vigorous plant which will require
root pruning in a container, in the ground it gets to greater than 30
feet, and of course has bold and striking leaves. Because of its
size not an ideal container tree.

'Garnet' (Garnet dissectum is an illegitimate name) is a mound forming
red dissectum, and like any dissectum it will need some training to
put on additional height. Getting one at the dimensions you want
might be quite dear. Also, I wouldn't plant one in the shade, I
think it will go quite green. If you want a dissectum you might try
'Pink Filigree', which will hold colour better.

'Burgundy Lace' holds its red very well in the shade, my friend has
rated this one 10/10 for colour in all day dappled shade. However any
red Japanese maple tends to green in shade, it's just a question of
degree. It is a much smaller tree than 'Bloodgood', also a little more
difficult to grow, but quite hardy. It tends to go wider but can be
pruned to the space. Certainly my choice among the three you name.

Otherwise as you have discovered, there are so many cultivars it's
hard to keep track of. For reds in shade I might also recommend 'Beni
Otake', or 'Red Pygmy', for linearlobums, 'Orangeola' or 'Red
Filigree' (or 'Pink Filigree') for a dissectum, 'Fireglow' for
another Anoenum that keeps colour well. 'Pixie' is a very
interesting dwarf that makes an ideal container plant and holds the
red very well in shade.

Yes the photos in the books are sometimes taken with strange lights or
at night, they are not very indicative of what the plants look like
(at times, other times they're OK).

That's very informative Emery, thanks. And very timely that there have
been a fair few posts about Acers over the weekend.

One of my first urg posts was about an Acer Garnet that I'd been given.
It was in a pot but unfortunately died over the winter (due to
waterlogging of the roots, by the look of it).

I am planning on replacing it and this time, due to the previous
issues, I think it will be planted out - once I decide where to put it
anyway . The only spot I have available at the moment would be be up
against a fence but on the North side, and further sheltered from one
side by a largish Willow.

I'd like to get one that is predominantly red-leaved but worry that
this might a bit too sheltered. Your post has certainly given me food
for thought and I will visit some of the better local garden centres
next weekend - maybe even Wisley.

--
Chris