Andrew, I would fish that without hesitation.
the profile is excellent, the hackle is right; not too long.
Again these are just my views, hardly definitive...
Something I noted many years ago, the loss of tails on wets and nymphs made little difference to the fish, having little effect on attractiveness.
I still tie them in of course;
well, I stopped and later, restarted for aesthetic reasons and authenticity; they are easier pulled off at the waterside, if req'd, than attached.
The tails on this one, Andrew, are just right for length IMHO; I prefer them to be fine, rather than fluffy.
I use a very silvery blue dun arucana rooster hackle to tail this fly as it is strong enough not to break off, yet soft.
Skues would have used Gallena,
as good as anything, having a valuable degree of stiffness, which is not excessive (Nymph Fishing for Chalk Stream trout, 1939 -page 104 & 114 in my reprint)
but as you see he was not really fussy, except regarding structure of barb
I reckon the tails are white because the natural spinner has white or very pale grey tails, the dun, grey.
The nymph ready for eclosion will have a gas-filled shuck with both of the above sequentially contained within, thus, white ( or in my case, silvery grey) should match the hatch, thank you Mr Skues for your learned opinion.
I am guessing that the nymphal shuck will be olive, a common trait to Baetis.
that might explain the addition of the dark wax. toning down the crimson body to imitate what will become the Little Claret Spinner.
I build this fly, as described, for clear streams; for peaty rivers I use also claret or purple thread, waxed clear, and water rat, a variant for sure.
As to the crimson wraps at the shoulder, I see that reference in the Dictionary, yet
not in the original 1939 Skues text.
A couple of years back, while health and wealth allowed me to get to the Catskill region, fishing the Beaverkill in a hatch at sundown, we had been told to use a size #18 Baetis nymph for the small BWO coming off.
Just on cue the hatch started and the browns were slashing through the top of the pool
When I went for a nymph, I did not have any in the box in hand.
Considering size to be more important than colour, I picked out a Dark Snipe, a deadly Baetis imitation for the Iron Blue in our north.
We had a busy three quarters of an hour before retiring for dinner.
So busy that the locals went home in disgust...
bloody foreigners coming over here and catching all our fish
I tie my nymph a bit less fat than yours; your fly being more faithful to the original.
Good work, sir
Roy
So it is up to me to learn how to fish them! 
The little 'stages' I set up for them are all shards of pottery and glass I pick out of my river when fishing.)]