I didn't want to hi-jack the other thread so this is going in a slightly different direction.
To sum up what has been said in the other thread.
There seems to be a general consensus that there is a need for different gouge cross sections and lengths.
You can use just about any gouge as long as it is ground to suit and used safely.
So my jumping off point here is the tool rest distance issue.
As the tool rest gets further away from the cutting surface there is a problem with tool strength and therefore a more robust gouge should be used.
So if you use a curved rest that fits pretty close to the bowl curvature then there should be no problem using a lighter section gouge with the same grind is the way I see it.
Having said that I can see no reason why a spindle gouge could not be used with a curved rest to hollow out bowls and also do the outside cuts.
So if you accept that (or not) then lets move on to grinds
The grind on a spindle gouge fresh from the maker normally has a square cutting tip with rounded corners. The assumption I always make is the maker just leaves it to the user to grind it the way they want it.
However in Frank Pain's book The Practical Wood Turner he offers this:
Which pretty well matches the grind on a new spindle gouge
I have never tried this grind in the manner he suggests but I have sharpened an LV European style forged gouge with the same grind and used it as a skew/roughing gouge on both spindles and the outside of bowls.
Anyway as you can see there are no simple rules about tools when it comes to turning. Everyone has their own approach and comfort level. Just from discussions like we have on this forum there is a lot to be digested and adapted