Martha Jane ballast

I have been following the ballast discussion with interest, i.e. more
is better, but I'd like to keep my intended MJ as light as possible
for trailering. I'm still unsure if I want to increase the ballast,
I have sailed on a MJ built from the original plans and thought she
was great. If I do decide to build mine with more ballast, would
there be any drawbacks in stretching the water ballast tanks to give
an equivalent water weight to that proposed for solid ballast? I
haven't read the MAIB discussion on the updates yet, maybe its
mentioned in there, but until then, can someone outline any pro's or
cons?

Col Mooney