Hi NurEinTier,
I was looking at getting a steel chainring when I built up my wife's bike. Surly seam to be the best bet but they only do a limited range in 104mm. 32t, 33t, 34t, 35t and 36t. In the end I decided it wasn't worth the trouble, I have now got 8000miles+ on the first side of my aluminum chainring and just like PH I expect to replace it 20,000miles.
As for the naughty gear combos well its defiantly at you own risk. As you are probably aware the minimum 'allowed gear ratio is 40:17 or 42:17 for a tandem. If you are a Olympic fit 120Kg rider then obviously going to generate more force into the hub that if you are a 65Kg occasional rider. At the end of the day it is you that is paying the cash so you will have to decide on this one! There are riders out there that do use the naughty combos there is also at least one story on the web of someone who managed to shear a drive pin by using a naughty combo. (Anyone know where this quote is - I know I have read it but cant find the details)
All the best
Stuart