When you switch your client and working with the same employer, you do not need to file for amendment, but just ta new lca with new client will work. Even when you go for stamping, take the new lca, as the consulate might ask you where you are working and if you have the lca. If you go with right documents you should be find on stamping.

And i havent heard H1b denied based on the info you provided. It might have been some case about the specialty occupation.

Hope this helps.

Thanks for your response Jobguruji,
Are you sure we can go for stamping without amendment?
If anybody did stamping without amendment, Please share your experience.

about H1 denied from Masters quota with Profit University degree. Please check below link:
http://forum.murthy.com/index.php?/topic/68596-extension-denied-masters-from-for-profit-university-not-considered-under-masters-quota-for-h-1b/

Yes, we haven't had any problems on the stamping. Amendment is necessary when there is significant change as in Job Title, or Duties or Salary, but just for the location change it is not necessary.
http://www.nationofimmigrators.com/INS%20Memorandum%20T%20Aleinikoff%20Amended%20H-1B%20Petitions.pdf

Thanks for sharing the link, will have to dig deeper on this.