This is one of the kinds of things that I keep my Wusthof and Henckels chefs around for -- that, and for loaning. I also think a bolstered Western handle, properly proportioned, is more comfortable when you need to use a lot of force -- no hard corners at transition points.
Beyond that, as a fellow lefty, if you go for a wa: I have a couple of standard D-shaped Japanese knives, and have zero problems using them left-handed. In sorting out this decision, I wouldn't worry about that particular issue a bit.
You might ask Mark more about the Ultimatum in 19c27 -- some of the reviews have suggested that while it's fairly thin at the spine, it's not overly so behind the edge. Not sure if it's sufficiently beefy for what you're considering, though.
For a symmetrical grind deba, you could look at Moritaka:http://www.chefknivestogo.com/moritakadeba1.html
It's a tank, but not stainless.
Ultimately, I think you'll have a hard time reconciling your desire for a Japanese 240mm gyuto that is also a beefy bone cutter. The DP deba is probably the closest compromise. If that isn't acceptable, I'd probably choose a knife in the style that best suited my primary use, and supplement with something cheaper for the secondary use. If you try to make it do too many contradictory things, what you end up with is at best a minivan, and at worst a Pontiac Aztek.