I've just picked one up, at that price I thought it's well worth trying on my bench.
My bench has been 'under development' for some time now, it a heavyweight 4" thick beech top and because my workshop is small and the bench is only 5' 8" long fitted against the longest wall of my workshop thats 9' 6" in length.
The bench is fitted with a Veritas twin screw vice and a tail vice with plenty of dog holes on the top and a thick skirt on the front to which i can clamp sheet material onto if i am working the edge, e.g. as i was this week planning ply draw bases to fit draw boxes.
I started with a longer bench in my old workshop with a Record 53 fitted to the LH end, but as the bench was over 7' long i never had a problem with the vice getting in my way when working on the bench top, i just moved further along the bench with the vice behind me (I'm a lefty so i work with the bench to my left side).
Back to my 'new' workshop i fitted the twin screw onto the front skirt despite the fitting instructions sugesting fitting this vice to the end. Over the next year or two i discovered i had made a big mistake as the vice was for ever getting in my way if i was working on the bench top, so i made the decision to reposition the bench slightly and mount the vice on the end of the bench, thereby freeing up the front face of all obstructions.
I then set about thinking about the time i might need a smaller vice on the front face and was considering of installing a leg vice, but again this could mean the front of the bench could end up with an obstruction along its face.
Soo... back to the parrot vice, i plan to mount it on a ¾" plywood base about 6" wide and 2' long, i can then clamp it in the twin screw vice, clamp it down onto the bench top or clamp it into my tail vice which will give me plenty of versitility for a small vice anywhere along the front of my bench.
For less than 25 quid i thought it was at least worth a try. I'll give it a go next week after I have finished my under bench draws and cupboard that i have been working on for far too long!