The Ambeo have a higher noise than the SPS200, but the SPS200 is a quiet microphone (12dB equivalent noise per capsule, 6dB more the Ambeo). The SPS200 are more prone to suffer by humidity (is a external polarization condenser) (I had problems with humidity but is very unusual), I belive that the Ambeo is more rugged to humidity due his electret elements.
The frequency response is better in high frequency in the Ambeo due his closer capsules (Less phase issues), the rest, much better the SPS200, specially with complex sounds (Music)
For ultra quiet noise the best IMMO is the Soundfield ST450 (Large Diaphragm Condenser)
IMO, the SPS200 is far better than the Ambeo (As suggest his price difference), but the Ambeo is nice for the price.