I was wondering if anyone has had experience of either of these flat soled spokeshaves. I am considering one of them for a bit of Greenland paddle making.

I certainly don't want to 'pour cold water' on any plan to get more tools... it is Christmas season, after all... ;-)
..but..

I've made a few Greenland paddles, and my main concern was in keeping everything straight and symmetrical. The very short bed of a shave isn't really suited to establishing long straight sections, IMO.
I found that a block plane was the ideal tool for most of the work (after roughing out with power saw). Holding the plane at a diagonal is handy in some areas, especially when working against the grain - and an adjustable mouth/throat can help as well.
Around the shoulders (assuming your paddle has them) a wood rasp was handy. For the oval part of the shaft a length of coarse sanding belt made converting the plane 'facets' into a smooth shape a quick job.
Most of the traditional GP shapes I've seen don't have concave sections, but if your design does, then a curved scraper or a small convex-base (luthier) plane may be the weapon of choice.

I have a small collection of spokeshaves, but don't use them much.