Hmmm…well I must say that the Callan looks lovely and yes, some small nylon/gut harps can be good with wire if you drop the range about 5 steps or more. The Triplett Zephyr is one such, so too the Music Maker Limerick. The issues one runs into are the bridge pins (not a good idea on a wire strung – they can kink the strings) and the soundboard is TOO responsive with softwood. With the very long ring that wire with a spruce or cedar board will echo FOREVER!! Which is why we use a thicker hardwood board.
This next is a tad heretical but I’ll go ahead and write it. High density laminate (aka aircraft grade Finnish birch) is a good though not great substitute for hardwood. That is what I have on my little 19 and I love it for just kicking back an noodling around.
If you are falling in love with wire strungs, why not ask Mr. Clallan to make you a custom one with hardwood or aircraft laminate board, and omitting the bridge pins? The material for something like that is not terribly expensive and labor is not either. I think my 19 took about 2 weeks to make, most of which was just waiting for glue and finish to dry; I’d guess that all told materials cost about $200. Most of that was the cost of strings since I had to buy WAY more than the little harp needed LOL.
Or of course keep the Ardival – they are just lovely harps! One final possibility would be to buy a Limerick kit and tell them you want tuning pegs put where the bridge pins would normally go ( and preferably have them drill and ream for #4 pegs). Those folks are very accommodating and I can send you the appropriate string chart (bronze or brass).
I do find the Limerick a bit heavier than necessary – the sides are 3/4″ thick – but it’s still not a bad little harp and 26 strings (“standard” spacing). The range on that modification is G an octave below middle C (G2) up to a D, yellow brass (or bronze) with the lowest two strings red brass.