I would ask them to explain HOW and WHY.  In detail.

I don't see this on their website and am skeptical about such a claim myself.  I think the details on their website are too skimpy to make a purchase - even at only $10/month.

W3C Validation: How Important is This to Ranking?

It depends who you ask.

If you ask one of the W3C evangelists they will tell you that you will never get good rankings without it and that google will penalize your website and not allow it to be seen in certain countries.

If you ask people who really know about this stuff they will tell you that if your site renders well in most browsers you will do fine in search.

Right now you have a problem with your best clients typing in NYCOfficeSpaceLeader.com or NYC-Office-Space-Leader.com or NYC_Office_Space_Leader.com (and a host of typos).

If you go to the proposed domain your best clients will be typing... MetroManhatten.nyc and MetroManhatten.com and Metro-Manhatten.com.

Those domains, to me, are like throwing traffic away.

Phone conversations go like this...

Guy: What's your website?

You: Metro hypen Manhattan.NYC

Guy:  Huh?  MetroHikingManhattan.com?

You:  No.     M-E-T-R-O hyphen-like-a-minus-sign M-A-N-H-A-T-T-A-N dot com

Guy:  huh?  can you repeat that ?

You:  OMG!

Guy:  OMG!

I would make the name of my biz really simple.  Get a good .com domain without hypens.  I'd be willing to spend good money to get an appropriate domain that anybody will clearly understand on a telephone.      If you don't get a .com then whoever owns the .com is going to get lots of your type-in traffic.

I got a request from a potential client as he do not understand why his website cannot be found on Google.

Honestly....  I think most of the people who say this know what they did but they ain't sayin'.

It is very easy to get information about Multiview....

http://www.yelp.com/biz/multiview-inc-irving-2

http://www.ripoffreport.com/reports/directory/multiview

I discovered that many other people share my opinion.