Well soy in and of itself isn't bad. But there are several issues that surround soy. Again it is one of those choices you read and make up your own mind. If money is your primary concern then buy the inexpensive food it won't hurt.
Soy when they say deforestation they mean rainforests. Many of the farmers around the
amazon and other rainforest areas are cutting trees down to grow more crops and one of the major crops is soybean. Not for their food but to sell to the soybean hungry world.
http://www.mongabay.com/external/soybeans2003.htm
In addition, there is the question of where is it coming from. Not all grain used for animal feed is US grain. I've listed the top 4 soy producers in the world. brazil and Argentina are where you see the rainforest destruction and China of course in my opinion is not to be trusted. If you are buying soy feed from a local mill you are ok but if you are buying it from a big agri company like Purina you can't be sure where the soy came from and what pesticides or other items where used in it's production. The other countries do not follow our growing guidelines and some still use persistant pesticides like DDT. You may not care about organic but you might should care about persistant chemicals as they pass through food and remain in poo and soil.
US
Brazil
Argentina
China
http://www.fao.org/es/ess/top/commo...3E8B1D92A620B2E2F9?lang=en&item=236&year=2005
Then soy has the allergy thing as well. It is one of the top 8 food allergens and it is very hard for those who need soy-free food to find it today as soy is in many processed foods. If you are going to sell your eggs soy-free can help increase the price.
http://www.mayoclinic.com/health/food-allergies/AA00057
Soy in quantity can change your hormonal balance. Well extra estrogen maybe helpful if you are going through menapause it isn't always helpful when you are going through puberty or your 20', 30', or 40's. The japanese mostly eat soy in a fermented process and we've started jamming it in everything. Soy isn't considered to be highly digestable.
There are lots of sites for the above.
That being said. do I eat soy yes some. Do I think soy is evil no. Do I think all chicken raisers have to go soy free no. Do I choose to go soy-free, yes. I can afford it and I already have a few buyers for my eggs lined up because my eggs are non-caged, organic, soy-free, non-GMO corn. My price per dozen is $3. which for the south (I'm in north florida) is good. My husband has a friend selling at work who gets 1.50/doz. I won't ever make a fortune but the increase price does help offset the cost of the feed. I also suppliment my girls diet with garden throw outs. Since I garden organic I have tomatoes that the ants got to, I grow them collards on purpose, we have left overs from our normal produce. I also have black soldier fly larvae (they happened in my compost I did nothing) and will soon be getting meal worms. I don't go through a ton of feed (or work).
These are personal choices and not everyones wallet or conscience will be the same. It isn't that one is right and one is wrong they are different.
Kiz