You are correct the direction antenna will affect the ability of the local PC to connect.
You are best off getting a device that has multiple antenna so you can have both types of antenna at the same time. I do not have a lot of experience with the 2 boxes you list but I have used hawkins hw2r1 box.
This box has different antenna for the remote connection and the local connection. If nothing else they have nice diagrams that discuss this issue.
I am thinking about buying a wifi access point to act as universal repeater in order to let laptops far away from the wifi modem router to get online as well. However, since I do not know whether this wifi AP will get enough signal with the antenna it brings, I am thinking of replacing the low gain antena(usually 2d it might bring with either a directional or an omnidirectional antenna. The question is: if I use a directional antenna pointing towards the wifi modem router, will still my laptops connected through the wifi AP get enough signal considering the new wifi AP's directional antenna is not going to be pointing towards these laptops but towards the wifi modem router?
That is to say,
Is it a good choice a directional antenna for access points which are not only connected to other wifi access points through wds or wifi universal repeater mode but have to give access to clients such as laptops with wifi cards?
By the way, I am thinking about buying any of these two wifi AP's:
150N Wireless AP/Bridge/Repeater Conceptronic.net
Which one would you recommend? I guess both of them match my purpose of using it in universal repeater mode, right?