2011 MacBook Pro, memory upgrade question

Does anyone know if the following memory is safe to buy (regarding compatibility) for an upgrade to a 2011, 13", 2,3 GHz, i5 MacBook Pro?
Has anyone used it?
If so, were there any problems?

http://www.amazon.co.uk/Kingston-apple-4G-1333Mhz-Module/dp/B00383L02I/ref=reg_hu-rd_add_1_dp

Searched the crucial site, saw an 8 GB kit they sell, but i read the discussions on the page and several people had a pretty non-functional machine after installing the new RAM, so i decided i'd better not buy that.

I found the above in amazon, which seems compatible (but i am not absolutely certain) and isn't much more expensive either.
After reading the stuff on the crucial site, i decided i should probably be more cautious before buying any RAM module, so if anyone has any knowledge/experience with the above RAM, share their opinion...

 

Well, believe me, i did search (otherwise i would have already bought the crucial kit).
However, i didn't find anything on whether the specific memory modules (that appear to be compatible) have any issues with the new macbook pro, or they work just fine.
As i already mentioned, there were posts saying their macbook wasn't working properly after installing the crucial memory, and they had to return it.
if the one in the link works fine, then nothing else to do but go ahead and buy it...

 

Did check macsales.
They had owc, which i can't find anywhere in Greece where i live, and Samsung, for which i couldn't find a 4GB module in local retailers.
(or amazon uk)
Macsales ships here, but the price would be skyrocketed, since the shipping would cost a bit more, but mainly because it probably would go through customs, making me pay additionally maybe even more than the memory costs in the first place.
So, i think i'll probably go for the kinston one.
I saw this site
http://www.canadaram.com/apple_macbook_pro.htm

where they list it as guarantied compatible.