Well, anybody interested in Gelas/Rowies should visit Palm Guitars in Amsterdam. They have literally the whole range: http://www.palmguitars.nl/large_img.php ... height=762
These can be interesting and good sounding instruments, but with older specimens, playability is almost always an issue, mainly because of high - and unadjustable - string action. Over the years I've had a few mandolins and a mandola pass through my hands, and had a go at restoring them, mainly to get them to play again.
It proved to be a nightmare, the reason being the not-so-well-thought-out construction.
This design revolves around two major 'innovations' (or so they must have seemed at the time): 1. the double soundboard, and 2. more significantly: the negative string-angle, with the strings pulling the (lower) soundboard upwards through the fixed (glued), non-adjustable bridge, instead of pressing downwards on a floating bridge.
Those of us who are familiar with the traditional arched-top floating-bridge principle will understand how this negative string-angle can turn out to be a double disadvantage. In the life of a 'normal' floating-bridge instrument, a non-reinforced neck will tend to pull upward over the years; however, in many cases this movement will simultaneously be compensated by a slight sinking of the instrument's top under the bridge's downward pressure. And then there's still the bridge itself that can be adjusted. So, although problems can arise, they will, in most cases, be manageable.
But with a negative string angle as in the Gelas, the 'compensation' is reversed into aggravation: the neck will pull up, and
the soundboard will pull up. And here the double soundboard construction is another disadvantage, because it allows for quite a bit of (subtle but crucial) distortion of the shape of the body. In other words: not just the neck and soundboard, but the whole body will tend to give.
Shave the saddle as low as she goes, but after that there's no choice than to (partly) rebuild the instrument, with the final outcome still very unpredictable. Well, both my (extensive) restorations looked very promising when I was finished, but after a few weeks every part of both instruments started moving again... in all the wrong directions.
So, the advice is... ONLY buy a Gelas/Rowies if it looks playable and there's still some saddle left. And, also be prepared that it will tolerate very little experimenting with string gauges, as well.
Or, the only safe bet in this respect... buy the Hawaiian.