Clevo / sager are most definitely the best bang for buck
the 4700 vs 4702 argument is that the 4702 uses less energy; but is a % worse.
you can get a cheaper version of the sager that has the 860M which is better than the 770M as it's the newest archetecture for a lower price at www.xoticpc.com (if you're in the US) or you can get an upgrade to the 870M which is even better.
you'll find that most branded laptops are overpriced when it comes to having a discrete (seperate) graphics card.
however; the sager WILL NEED AN OPERATING SYSTEM / SELECT IT IN THE OPTIONS, since they come as empty partitions
I want better value for money product. I know that sager has better hardware (770M vs 750 and 16GB vs 8 GB RAM ). I have also read that 4700 MQ is better than 4702MQ. Is it SO?
Is this hardware difference worth the extra money?
There is very little difference between the two processors. The 4702 is ever so slightly slower at the advantage of having a lower TDP, but that's not a big deal and Sager's are designed to handle high thermal activity anyway. As for your concern on the GPUs, the new 8xxM cards are pretty good. A 860M will perform about as good (not equally, but approximately) as a 770M, while a 870M performance should be between 770M and 780M. A 880M will outperform the lot of them.
I think if you want the best value for your money, the Sager will last you as long - if not longer - than the HP as long as you take care of it!