They will all indeed catch fish, a few pointers to help you out:
I would leave out the peacock herl, I've had way more success with the original dressing of just using the pheasant tail, plus its delicate and if a trout gets his teeth round it it'll more than likley snap.
Also you can afford to tie the tail in maybe 2-3mm further back on the hook shank, makes for a more proportioned fly, 2/3 body 1/3 thorax. You can use thi rule for your tails also, same legnth as the thorax, 1/3 hook shank legnth.
This is how I tie my small Pheasant Tails ( 14 or smaller):
Take thread to end of hook shank and tie tails in using 2 wraps of thread, apply a thin coat of super glue to all of the hook shank, take the pheasant tail all the way to the eye of the hook (leave room for the head), the use the tying thread to rib the body (aim for 6 turns of ribbing), take one turn 1/3 down the hook shank to where the back of the thorax will be, now fold the fibres back over for one pass of your thorax cover, tie down with 2 wraps, take the tying thread back to the eye and bring the fibres back again over the thorax, tie down snip off and whip finish, job done. I use 5 fibres for a size 14 4 for a 16, this seems to give a good impression of a tail without over doing it.
Hope this helps.