I have a friend that feels it is his duty to tie flies religiously according to posted recipes for that fly, this includes using some longer-shanked hooks for bead-head flies. I for one can't see it. I agree with Fred, let the fish decide.
I have tied for a lot of years and became a bit of a rebel when it came to buying higher priced, name-brand hooks that seemed to be called for in many recipes. Bead heads came along and sure enough there was a move towards specific models designed for beads or a recommendation that one use a longer shank for the bead-head fly, and they priced them a bit higher and called them a specialty hook. I now tie the majority of my flies (dries, nymphs, bead-heads, emergers, etc.) on one style and model
of hook - Dai Riki 125 Emerger hook, a brand that is about 1/2 the price of many of the popular brands referenced in most recipes. Allen also has some similar hooks that are much less expensive than the popular brands.
Here's how I see it - if I were to use a longer shank for a bead-head pattern then the fly is usually out of proportion by at least the extra length of the longer shank hook. Just my opinion. Yes, you could re-design the pattern to fit the hook, which is really what I'm advocating here - you decide. There have been many newer patterns developed using beads and longer hooks - I say, tie them that way if you want. There is nothing in any rule book that says we as fly tiers need to follow prescribed recipes for any flies, unless it be complicated Atlantic Salmon flies and such. In fact, I don't think I've ever seen a rule book...
I know there are a few purists here who will call me a heretic, thus the fact that this is my belief and I force it on no one
Google a Pheasant-tail nymph and go to the "images" results and you will see as many different versions as there are hooks and then some. Now Google Frank Sawyers original PT nymph and look at how different it is from what we consider to be a standard PT nymph in today's world. They all catch fish!
I'm not attacking the premise of your question, just giving my opinion as a long-time and experienced fly tier who feels it's okay to be as creative as you like as long as the fish you catch with your creations continue to like them as well.
Here is an example:
I tie a Bead-head, flashback Pheasant-tail nymph with a DaiRiki 125 emerger hook. This hook is light wire, 2x short, with a hook gape about 2 times wider than normal hooks (which leads, in my opinion, to more hookups, especially in smaller sized flies). Why do I use this particular hook? I like the way the finished nymph turns out - notice I said, "I like...". Part two of the equation as to why I use this particular hook and recipe is because I catch the majority of my trout on this pattern in hook sizes 16 and 14 - which means that the fish like it also. Also, I do not use a prescribed recipe other than that I do use Pheasant-tail fibers for the tails and to wrap up the abdomen, and peacock for the thorax. After that I have made some changes that result in the finished fly that I and the fish like.
So, your original question asked if I use or prefer longer shanked hooks for tying bead-head flies, and my answer is no, I prefer using shorter shanked hooks to achieved my desired results. All of my patterns I tie are a result of using tried and true recipes, perfecting tying methods after much practice, and then having the confidence to experiment, and then find out what the fish prefer.
Long answer, I know, but I don't think there is a right or wrong answer, just the right answer for you and the fish to whom you present your finished flies.
Here is a photo of my finished Bead-head, Flashback Pheasant-tail Nymph that I use everywhere I fish for trout:
Hook: DaiRiki 125, sizes 16-14
Thread: UTC Ultra, brown or black
Bead: 3/32 Copper colored brass bead
Tails/Abdomen: Natural brown pheasant-tail fibers - 6 to 8
Wire rib: Chartreuse, small size
Abdomen flashback: UTC Mirage, opal, medium
Wing-case Flashback: UTC Mirage, opal, large
Thorax: Peacock herl
Legs: Hen saddle hackle, mottled brown
Here is the same hook used for a dry fly:
And, a small midge:
So many options and opportunities. Let your creative juices flow and then give the results a try in front of some hungry fish!
So, simple and short answer to your original question, No, I don't use longer-shanked hooks to tie bead-head flies...