WE had it done last year right before dd was born. The amount of "stuff" that was sucked out was disgusting! So it's def worth getting all that nastiness out, so you're not breathing it in. I have eczema and bad allergies as well and I honestly did not see any difference in them for myself. It's hard to say with dd b/c she wasn't born yet when we had it done. I think it cost us like $300.
I work for my dad who owns an air conditioning company, and we do not offer that service. The main reason being, yes, it does take all the junk out of the ducts, but the next time yo use it, they are filthy again. And it doesn't make a huge different with the air quality.
Re: Sorta NBR: Heating ducts