Yeah, that's why it doesn't do as well against left spin defense, however, the applications of left spin defence are rather narrow, as they suffer the same issues against right spin beys (like Basalt BD145) the Right Spin defence suffers against Left Spin attack.
I think against left spin attack, it comes down to this combo being heavier, and this is compounded by the rarity of Rubber-Tipped left spin attackers other than other LT's, in the metagame right now, as they're often taken out by other common combo's.
Anyway, I believe this is the video. I'm not sure if it shows the Weak Launch thing (I haven't had time to watch it), but it does demonstrate the spin stealing:
http://www.youtube.com/watch?v=bLUvQi5WWXU
I think people should watch it in case it answers their questions
The wear on LRF would make a big difference to the spin steal there, obviously. It does show it can spin steal effectively, anyway.
And if you look at the end of those battles, it's exhibiting the defensive characteristics which would occur from a weak launch. The spin stealing would compensate for a lot of the speed difference of the opponent if you launched weak at the start of the battle, methinks. The next question is if you'd have to worry about being KO'd by whatever you're launching weakly against.
That said, do remember that often, BD145's protection and the weight and grip of the bey should protect it from attack types.