Just a note on PhotoScanning.ca - We are in a much different boat serving a different market than the three competitors you mention there.
PhotoScanning.ca targets consumers looking to have photos digitized in bulk, quickly and in a cost effective manner (hence the guaranteed lowest pricing in Canada).
I'm sure the other three companies mentioned there are great at what they do - but they are most certainly going to spend more time on each image than we would. Our service is about scanning thousands and thousands of photographs (We've had orders >30,000 photos!) for preservation, while those companies appear to be looking to maximize image quality and details within each image. Along with this, they are between 5 and 50 times our price. I'll be the first to say that they will give you a higher quality image, but where we excel is in the bulk orders. I've actually sent a few clients to other services for a small number of photos (I.e. they get 1200 done with us, and take 10-20 that they'd like blown up for prints, or are very fragile, etc).
This being said, our service isn't "bad" quality, it just isn't the rolls royce. Here is an example of our service (left) compared with a scan from a Creo Eversmart scanner - these are raw scans, i.e. basically "full auto mode", not edited in PS, etc.
Click to view - http://i41.tinypic.com/e7hwxx.jpg
As you can see, the creo has a higher dynamic range, picks up shadow/highlight details better, and is sharper. That being said, 99.9% of our customers are very pleased with the quality of the scan they are receiving in comparison to the price difference. Now again these are both raw scans, no tweaking or restoration (which is a service that the companies above are likely fantastic at, and something we do NOT do)
Again I'd like to stress that the other companies are likely fantastic at what they do, but we're an apple where as they are an orange
I know we've had a number of customers on local forums, so hopefully someone will be able to give you some first hand experience as well.