I would wait now with the transformation.
There are lot of talka about the incompabilities in tigers and leopards software raids atm.
Something about the tigers sr 3.6.4 not being recongized by leopards,3.6.5. The 3.6.6 is rumored to release in the next few weeks.
Dont know if then the problem will be solved? I mean, if your softwareraid version is higher than on the leopards installation disk,will that cause conflicts?