I have a "garnet" planted pretty much in a location as you describe.
It must be 6 to 8 years in that location.
It is not yet 6 feet tall, but is way more than 6 feet wide.
Planting anything under a weeping maple usually does not work unless it is a dwarf shrub (like pittisporum "taiba") or low groundcover.

Takes CA summer sun well & the color does hold. I don't water it much during our rainless summers once it became established in this location.
It is a very beautiful tree. Bought, as I say, many years ago for 30 bucks or so to give you some idea of how big (expensive$$$$) it was then. They grow fairly slowly.

Crimson Queens are pretty nice too. Mine are in containers.

I would take the time to carefully examine the shapes of any prospective purchases. Some trees have much nicer potentials than others in terms of existing branching.

I have both Garnet and Crimson Queen in my yard and would recommend CQ for several reasons. It holds its red color much better and longer than Garnet. It will not grow as tall or wide as Garnet. Both varieties will take a fair amount of sun, which will also help them keep their red coloration better.

I've had my Crimson Queen for about 15 years and have moved it several times. The spot where it has grown the past 10 years used to get quite a bit of hot afternoon sun and it did fine, although it looks even better now that the spot gets a little more shade as the trees in my yard get larger. After 15 years (and tree was several years old when I got it), my CQ is about 4-5' tall and 5-6' wide. Its leaves are deep reddish purple and turn crimson in the fall.

I've had my Garnet about 2 years and it was fairly large (3' tall and wide) when I got it. It has beautiful reddish orange leaves in spring but quickly starts greening up and loses much of its red coloration by June. Mine is growing in a fairly shady location, and it would hold its color much longer in a sunny spot but I still don't think it would last as long as CQ. Garnet is very fast growing for a dissectum JM, which can be good and bad. It's good if you are looking for quick impact and have lots of room for a tree to grow, but it's bad if your space is limited. Garnet also has crimson leaves in fall.

If you can find a Red Dragon, that is my personal favorite red dissectum. It has the brightest red leaves of any variety I have seen and keeps its color well in shade or sun. It is slow growing, however, and relatively unproven compared to Crimson Queen, which is one of the old standby varieties. If you can find a nice Red Dragon go for it, but don't feel bad if you have to "settle" for Crimson Queen, which is still a topnotch variety.

Regarding Japanese beetles, we have a lot of them in my yard but they never bother my Japanese maples. That doesn't mean they won't in your yard, but they find other things they prefer in my yard -- such as crepe myrtles, various vines and flowers. They love roses.

That's a good suggestion about the branching. I need a tree that will provide winter interest, and the bed has two good size boulders that I want the branches to cascade over --eventually. Yesterday I found another variety at a local nursery (well, sort of local): Inabe Shidare.

They also had some Crimson Queens that were a bit smaller than the ones at the wholesale place. And a lot less expensive, $69 compared to $250. But the shapes were not inspiring--basically a long trunk with a few branches sprouting off the top. I don't have enough experience to know if this was due to the tree's youth, a lack of pruning, or both. The Inaba Shidare trees were larger with interesting branching, the nicest ones being, once again, $250.

Either tree would do fine and either tree may show some burn in full sun...but unless you are a picky sort it probabkly won't bother you ...As far as ja beatles YES they do attack JM's ...mine were really hit last summer some varieties not at all other alot ..If I remember right my CC's did not get infested...seven spray will kill em dead but you got to treat often ...a big wholesle nursery in I think NC was really hit ...so yes they do attack at least some cultivars.Crimson quees are available EVERYWHERE even at K mart at bargain prices...You may want to give Della a buzz or wemail she just got in a big shipment of stuff and she doesn't live too far away ...don't know how may dissectums she has but she does have garnet which is a really nice tree that grows fast!!!.. http://nurserygirl1.tripod.com/index.htm

David

Thanks, this makes me want to take another look at the Crimson Queen. I don't want fast growth in this bed since it's between two walkways or need it since I already have those nice boulders and azaleas. I may even be able to get away with a younger (read less expensive) tree.

I took a look at nurserygirl's website. And you're right that she doesn't live far away--as the crow flies at least. It's just that there're a couple of pesky little mountain ranges in between!