First off, using my Coronardo PST I can reach focus with these Binoviews. As I purchased them primarily for this reason they are a great success. It took a few viewing sessions to get use to them but the improvement in viewing the Sun through them is amazing.
As always excellent advice and service from FLO.

To cut a long story short, I have the Williams Optics Binoviewers which give fantastic views in my Tak 100DC but they require a bit of faffing around. Merging the images can be a bit tricky, I need to use the GPC to get focus. The GPC threads will not work with the Tak diagonal. I can only use them without the GPC by unscrewing parts of the OTA. They simply will not come to focus when used with a Lunt 50. But, they do give fantastic views.
I thought these Linear Binoviewers might solve a lot of the problems so I gave them a go.
The good:
Merging the images is no problem, even using high power eyepieces.
They are very well made and feel very solid.
They work without the need for a GPC.
They come to focus with the Lunt 50, though only with certain eyepieces (so far Televue Plossl 15mm and BCO 10mm). And the images with the Lunt 50 are very good. I find it much easier observing with the Binoviewers than with mono.
The not so good:
The undercuts do not work with the Tak prism. This can be worked around.
Terrestrial viewing (for example dark tree twigs against a bright background) shows a fair amount of false colour. This was also evident in white light solar at the sun's limb. It was not visible when observing the moon in the late afternoon blue sky.
The view is simply not as sharp or contrasty as with the Williams Optics Binoviewers. This is why they are only getting 3 stars.
Caveats:
I've only been able to compare them with the WO, observing the sun in white light (3 sessions) and the moon against a bright blue late afternoon sky (1 session). So it's early days but in each session the WO outperformed the Stella Lyra.
I will keep them though as they are great with the Lunt.