So let us assume Harry is not bashing, but just a little pessimistic. I love to be a devils advocate too.

POET will be a severe threat to a lot of well established companies. So in this war vs. Si POET will face enemies which possibly will play unfair. It is about huge investments, big money is involved. The opponents could be worse then any devil! So it is worth to face possible scenarios!

I can see only a few potential risks for POET, which could cause a higher then expected production price or problems with public acceptance, and press POET to a niche market, which still could be highly profitable (space, weapon technology, server market or high speed number crunchers will accept any high price for the best solutions)

1. The jeeld and cost of production

2. The tox profile of GaAs. Here it is about public opinion...

For 1. I hope the experts of the foundry world will find solutions (e.g. production of high purity GaAs wafers with bigger then the usual standard diameter, or epitaxy of GaAs on high diameter Si-wafers. All these problems can be solved...

For 2. It is a fact that - compared to Si - GaAs and its precursors in production are highly toxic, carcinogen, tratogenetic...

As a chemist I can tell you a lot about market acceptance and populistic reports. (best example: in an article about Potassium Nitrate - fertilizers I could once read that Potassium is highly aggressive causing burns on skin, and will self-ignite when in contact with water. Obviously they mixed up Potassium (the metal) with its salt. Gosh, such things are incredible - but reality.
(OT: I guess Rainer also knows a lot about safe nuclear technology and its acceptance.)

So we just have to see that the toxicity of GaAs can be used as weapons against POET. As we all know GaAs is present in most RF-chips (in cellphones) or in white LED. But this danger can not be neglected completely. As an example GaAs was discussed to be set on the ban list of the European REACH (http://en.wikipedia.org/wiki/Registration,_Evaluation,_Authorisation_and_Restriction_of_Chemicals) similar to the US TSCA).

It could have been a good reason to keep poet in stealth also because of such - unfair - discussions. To avoid such battles too early. So let us see how POET will fight. I am optimistic and hope that the best technology - POET - will win.
Happy NewYear, my friends!!!