A:
The EX2700 and WN3000RP are very similar. Allegedly, the WN3000RP has better electronics and provides extra help when setting up. That doesn't necessarily mean the WN3000RP will be much faster than the EX2700 because both are N300 extenders. The WN3000RP is considerably more expensive.
You should consider getting a dual-band extender that supports both 2.4 GHz and 5 GHz in order to take advantage of the 5 GHz band provided by your Bright Box 2. While 5 GHz does have less range, a weaker signal does not necessarily mean that it will be slower. Fewer people use 5 GHz, wider Wi-Fi channels are available to carry more bandwidth and superior Wi-Fi protocols are available. In the last case, if your Bright Box 2 supports 802.11ac, then speeds could be much, much faster.