Tidy work Barry and well done Jim :party:
Re getting kegs in and out of the freezer, mounting castors with brakes on the corners of the freezer would allow you to move the freezer to get kegs in, then, if you have the clearance at the front you could mount the lid so it opens forward. Alternatively you could mount the lid on one side if you have the 'head room' for the lid....just ideas.
Re the beer, there is good reason for the difference in the beer and the way it's served, sparkler v non sparkler...I can't remember where I read it, but it's something along the lines of... sparkled beer has a smoother/creamier mouth taste due to smaller C02 bubbles in solution, and less C02 (they get knocked out/decreased in size by the turbulence and pressure at the sparkler head) and a less intense hop taste but increased hop aroma initially. The hop aroma and taste side of thing is due to volatile oils and other compounds being 'knocked out' of the beer into the head, which is also why the head may have a more deeply perceived bitterness than the rest of the pint. Naturally, non sparkled has non of these factors and can appear 'fresher' than a sparkled pint. You have to remember you are not serving like for like, non sparkled will have a much higher carbonation level than sparkled and again IIRC trials showed the presence of more C02 both detracted from certain aspects and increased others.
Personally, I think there's only one way to serve through a beer engine and that's the way you like it...me, I prefer sparkled as apart from the taste side of things, minimising C02 content minimises the size my belly bloats to :lol:
I'll try and find the source of those comments but don't hold your breath