It isn't as vigorous as a grafted specimen (grafted on generic 'green' a.p.), but it does grow. I would class it as 'weak' compared tao generic 'green' a.p., a.p. 'Orange Dream', and generaic acer shirasawanum, which I think are classed as quite vigorous growers (period).
I do not recommend Uki for bonsai for the reasons similar to why I do not recommend EWP (p. strobus) - I think they are seriously challenging to make into refined bonsai (truth be known, ALL species are seriously challenging for me, these two are a little bit more so). They are, however, interesting horticulturally and entertaining challenges for those who like 'exploring'. I chime up with encouragement when I encounter seeming birds of a feather. I think it surprising how attractive Ukigumo can be and that it is a worthy subject for "wasting one's time'.
One who is seriously intent on making a maple bonsai should just get a generic 'green' a.p. or a small leafed buergerianum. Grow from seed, start with 50 whips produced to be grafting roots stock. a 5+ year old garden center 'specimen' and/or air-layers of it, or an almost bonsai. All you will need to do is read, follow directions, and patiently stick with it - you are likely to succeed in making a nice bonsai (not that there is anything wrong with that).