New hardware procurement

i am a student of telecommunications. we are undertaking a project
regarding
cooperative relaying using usrp. i have gone through some reports and
blogs
and that has made me confused about the selection of the daughter
boards.

there are problems such as strong line of site (which is bad for
relaying
diversity experiments) associated with 2.4G board with a low
transmission
power. on the other hand the flex400 has a lesser line of site issue but
the
transmission power is high.
are there any hardware issues regarding these boards?

what would be a good buy? flex400s or the RFX2400s.
thanks