What an interesting tree you are considering! Robinia pseudoacacia ‘Lace Lady’ or ‘Twisty Baby’ was a chance mutation of the species discovered among a crop of seedlings in New Zealand in 1985.
According to the Missouri Botanical Gardens, this cultivar is a deciduous, multi-stemmed shrub or small tree which is noted for its shrubby growth habit, zigzag branching and curling of some of the mature leaflets. It is approximately 8-10′ tall by 12-15′ wide over 30 years. It is sold by nurseries in several different forms: (1) a multi-stemmed shrub, (2) a single trunk tree or (3) a top-grafted tree to a 6′ standard. Trees feature a loose crown and fail to develop a strong central leader. It features pinnately compound, dark green/blue leaves (leaflets to 7/8″ long) which turn yellow in fall. This cultivar rarely produces the racemes of fragrant white flowers in May or resulting seed pods that are typical of the species.
Growers of the tree feel it does best in full sun to partial shade. It is very adaptable to both dry and moist growing conditions, but will not tolerate any standing water. It is not particular as to soil type or pH, and is able to handle environmental salt. It is highly tolerant of urban pollution and will even thrive in inner city environments.
Another nursery listed this is “a high maintenance shrub” that will require regular care and upkeep. It is best pruned in late winter once the threat of extreme cold has passed. One garden forum said it is non-suckering unlike others in the black locust family. Apparently rabbits love them!
It is noted that borers can be a significant problem in some areas. These trees are also susceptible to scale, leaf miner, leaf spot, powdery mildew and canker. Branches are susceptible to winter injury from heavy snows or ice. Since this is a concern of yours in your area, perhaps you could reach out to the Ottawa Master Gardeners for their insight at http://www.mgottawa.ca/CONTACT_US.php
I hope this is helpful in making your decision.