I work a lot with some the old once a year bloomers
you might waht to try grafting a bud on to a mature vigorous rootstock.
Hi Baxter, I can understand you being partial to large shrub types. I have made some crosses with species or near species type roses that like to get large before blooming. My strategy though in using these roses is to capture specific traits and then to breed for floriferous, more compact plants (though I wouldn’t mind larger plant habit just so long there was abundant bloom to go along with the plant.) I tend to think that plants that are reluctanct to bloom after 3 years will likely bloom only sparsely when they finally do bloom. Though I love clean glossy foliage on a well branched plant, I think a seedling is usually nicer when it carries lots of blooms. So I have tended to discard seedlings that are too rangey.
If your space is limited, growing cuttings would probably only use up more space and would probably not advance appreciably blooming time.
There are plenty of modern roses that have traits that you describe that can produce nice large shrubby plants that might be worth trying.
This is just my opinion from my own experiences.
Jim Sproul