Maybe not the best choice for your purposes. Provided it survives (more about that later), it could exceed your size requirements, especially with regards to width. And pruning a JM to size is not a recommended practice :-) It is also a very solid and dense, dumpy little tree and has none of the grace or sculptural appearance of one of the weeping laceleaf maples.

There are lots of red laceleafs to choose from - Tamukeyama, Inaba Shidare, Red Select. Crimson Queen, Red Dragon, Ever Red, Garnet, Black Lace, etc. Most are low, mounding forms but can get wide....usually they are wider than tall.

These are all going to be grafted plants and where the graft is located will determine how tall the tree is likely to get. A low graft will make a low mounded tree. A higher graft will provide more spacing/branching and produce something that is a bit more layered and sculptural. Always remove any staking as that will encourage vertical growth, which you do not want. Unless trained or encouraged to grow upwards, laceleaf maples just layer branches on top of each other in a very layered, horizontal plane.

Hardiness in your climate will be an issue. Zone 5 is considered borderline for many cultivars and zone 4 is questionable. Bloodgoods you may see around town are not really representational as they are essentially a red leaved form of the species and tough as nails! Of the red laceleafs, Tamukeyama and Inaba Shidare are often recommended for colder locations. Good dark, wine-red foliage as well.

Thank you very much! I will look into those suggestions!

I should add it's more like a 5b climate... my backyard is quite a bit colder due to north wind exposure... this spot is sheltered and I am convinced it is a few degrees warmer that other areas. It is basically a microclimate.

Excellent! Microclimates are good :-) As is shelter from winter winds.

Checked out those suggestions. Noticed that pretty much all fo them exceed 10' and generally more that 12' - I am wondering if I should rethink this and consider another dark-leaved shrub. I've had success with monlo nine bark, although I wouldn't mind considering something else as I have three on my property (though these are all in the backyard. Any other dark-leaved shrubs (preferably something that flowers at some point in the spring) ? What about dervilla (sp)?

Here are some picks of the planting site. The shrub will be plunked right down in front of that window. I also have a fothergilla that I intend to move in there. There's quite bit of space, length-wise behind those junipers (at least 15') so I was thinking a grass behind the juniper and dark-leaved shrub in the middle and perhaps the fothergilla on the left side.

How about Sambucus ‘Black Lace’ or one of the other dark leaved elderberries?

splaker, if you select a low grafted form of any of the ones I suggested (with the exception of Crimson Queen), they will never get taller than maybe 6'.....and that's at the upper end!! Some will never exceed 3'. This is not something you can just read about or pick out of a catalogue because they will rarely ever discuss where the graft is located or how the tree was trained. For best results you need in-person selection.

This is what you are looking for - or something similar:

This is 'Tamukeyama' with a low graft - it is a low, spreading mound not more than 3' tall if that. and has not been staked or trained for any unnecessary vertical growth. Any new branches that emerge from the canopy crown will just layer over the existing branch structure. Height increases over time in inches, not feet.

Would this not work for your purposes?

Yes, GG, that is very pretty... I guess I should avoid reading the descriptions from various nurseries, like Monrovia etc... I assume these are extremely slow growing to begin with so I suppose I will be 6' underground before this plant exceeds the site! Around here (north of Toronto), the housing market is so hot/crazy that many homes don't seem to last more than 4 decades before someone buys it and tears it down to build something bigger. I suppose I shouldn't be thinking about 50 years done the road!

Given that this plant would be on the northern end of its cold tolerance, is it advisable to shelter it in the winter? Perhaps some type of burlap? Yes, the spot is in a bit microclimate... but we can get down to -30 C some years... more. typically, -25 C a few times per winter. The site will be sheltered for heavy NW winds at least.

came across this and I think I prefer this palmate leaves over the thread leaf... Any experience with this plant? Looks great.. hardy to Z5 and it is sold in a couple of nursery up here...

Acer palmatum ‘Oregon Sunset’

A perfectly nice choice! And one that should suit your sizing requirements, at least for a number of years. In my climate, I would be concerned with it exceeding the height and space allowed but doubt JM's grow quite as rapidly or robustly in your zone and location :-)