Upgrade freehub body - practical / worth it?

[philtalksbx]

For a new project I am upgrading a bike from 7 speed to 9 speed Shimano. It has a lovely 7 speed wheelset that I built last year with new Open Pro rims on some buttery smooth hubs. Is it practical to swap the freehub body or am I better off just buying new wheels and selling on the existing wheelset? I guess the swap would need a replacement axle as well (also longer) and I will need to re-dish the wheel which I hope should be ok with the existing spokes as it will only be 1.5mm out. Otherwise it starts to look complicated and costly. Any thoughts / recommendations?

 

[Ajax Bay]

As you know the 7sp freehub won't take a 9sp cassette.
The 7sp freehub will screw off (big allen key) and a 8/9sp will screw on. The 7sp freehub has residual value.
The OLD will still be 130mm so a longer axle is absolutely not needed - bit of spacer replacement/selection, maybe.
So I think it's worth going for, including a simple redishing ?2.3mm?, and the spokes, provided the right hand side ones are not obstructing the nipple slot already, will be fine.
I have not done this transformation.

 

[the snail]

If you keep the same hub and OLN, why would you need to re-dish the wheel?

 

[Ajax Bay]

@the snail The 8-10sp freehub is longer than the 7sp freehub ie the dimension from RHS flange edge to lock nut is greater. This shifts the main part of the hub left by about 2mm left, hence the need to shift the rim right (compared to the flanges). But as said "I have not done this transformation".