Traditional Irish Music
I owned the non-tunable Optima shown shown on Piper's Grip http://pipersgrip.50webs.com/Optima.html and it was my first whistle a year ago. Within three months I traded up to a Goldie Low D which I haven't regretted but I still wish I had the Optima which I think is an excellent low whistle as well as being a good first instrument. The review is, I think, accurate. Tonally it is very rich though it doesn't compare with an Overton/Goldie but for the price it is an amazing instrument. Air requirement surprised me, as at 57 and unfit, I never thought I'd be able to play a low D and not without prior experience on a high whistle. Back pressure was moderate. Ease of play? What can I say? I picked it up and started to play it and it didn't suffer the clogging problems of an all-metal instrument. As the review says the low notes are a little sensitive but not excessively so. Reach I found easy though my hands aren't small. Go for it i would say. I love my Goldies but if I had the spare cash and a non-tunable Optima cropped up I think I would buy it back.
I would just add this. Marc Duff told me that while he owned all tunable Goldies, he liked the sound of a non-tunable Goldie - no disturbances in the tube due to the joint I guess. And non-tunables have low maintenance issues so there are advantages to them.