Every year we get some local contractors sold on the Polyurethane Foam. They go to The World of Concrete show in Las Vegas, take out a second mortgage on their home and come back with the Equipment and fancy marketing material.
It's always the same. 
"Look at these pictures of the mud jackers. These jobs failed."
"The Mud Jackers are Dinosaurs, a dying breed. They use obsolete technology." Folks, the Obsolete Technology one works because we are conditioned to think newer is always better.
FACT: We agree somewhat that Mudjackers are a dying breed. We don't use MUD.
FACT: They don't use pictures of our jobs, they find others as we do have competitors and most of their jobs usually fail. They show our competitors jobs, not our work.
We aren't saying our jobs never fail, but when they do, we come out and fix them. We challenge these foam guys to find one single unsatisfied ConcreteJacking customer. They can't.

Really the "The Newest Thing?" Polyurethane Foam has been around since the beginning of World War II where it was used primarily in the insulation industry and only in the last 15 years have marketing companies tried to adapt it to the concrete industry. They are making a lot of claims so you need to get the facts.
One important fact is the Cost. Their numbers usually come in higher but lately, the current crop are discounting their prices because they are in serious trouble. They lower their prices to try and get a few jobs or they go out of business.
Here's the kicker...they ALWAYS include a contract with an escalator clause that if they use more material than expected, you pay more. We have NEVER seen a job where they didn't activate this clause, and guess what, you are Locked in, you signed a contract.

One of the points they continually make is "The holes we drill are much smaller."
That's like saying after you use a different color of paint on a touch-up of your kitchen drawers, "Oh, it looks close, it's only a small touch-up." Wouldn't you use the same color of paint?
Isn't the issue How it Looks, not how big? We match the patch and after even just a few months, after it's completely cured and hard to spot.

There is a place for the Foam and it's NOT in Concrete Raising. It's been used for years in insulation and void fill but there are serious issues in Raising. Think about it. You are going to try and raise concrete that will weigh from 5,000 to 35,000 lbs. with foam that I can rip apart and even crush in my hand. I can show you 9 failures from just the past few years (A few listed here.) We have already fixed five and are on schedule for three more.
So why do the manufacturers at these concrete shows push it?
Consider this. Say I'm an equipment manufacturer. I sell you a machine. I now only have a future opportunity of selling you parts.
BUT, if I sell you a Foam machine, I not only get your parts business but All the material you put through that machine, on every job you do. And I'll include a disclaimer that I'm not responsible for any warranty, you are. Good deal for me, bad deal for you and the consumer.
Now you see why most of these Foam guys usually go out of business in just a few years.

Their marketing makes a lot of claims.
"The Foam will not deteriorate." False. Water and the Sun's UV Rays will cause deterioration.
"You get 100% compaction." False. The product has millions of microscopic air holes. How else could I crush it or rip it apart with my hands?
"We Fill the Voids." You be the judge. Watch the video just above. They try to get around the fact that their material won't travel far by drilling LOTS of holes as they know the void isn't filled properly.
MudJacking adds weight to the slab and will pull it down whereas ours won't. False. They keep referring to the term "mudjacking", which is an old term used in the mid-west. Our material does NOT stick to the concrete slab, in fact even  concrete will not stick to existing concrete. Again, assuming you are ignorant.   
"It's Totally Safe." By law, if asked they must supply an MSDS Sheet (Material Safety Data Sheet) which lists Poly Diisocyanate as a primary ingredient. Google it, judge for yourself.
We will readily supply the MSDS sheet for our product which is Gravel, Crushed Granite, Sand and a special Dirt we import.
And while you are reading their MSDS sheet, note the part about it being flamable. Granted the chances of something burning under concrete are remote at best but it's good to know.

Good luck. I used to have an associate in Utah County who added it just to cover those customers who insist on using foam. I brought him in on a couple of jobs in Weber County and he beat the other Foam guys pricing, but now even he is out of business.
If you have bought into the hype and insist on foam I certainly wish you all the best, but chances are in a couple of years you will be back to square one and realize you wasted your money.
The current crop of contractors say they will warranty but NONE of them have been in business for over two years. Talk to the owners of the jobs we show above and ask them how that warranty turned out.