Best is to listen and judge for yourself as others here have mentioned. I've listened to the 1.7s driven by the latest Bryston 4B-SST few months ago. That was the first time I listened to a pair of planar speakers. Couldn't warm up to the sound although they do exhibit a total lack of boxiness. The 1.7s are definitely very detailed and transparent speakers. However, sound of instruments will not have the body or tonal qualities of box speakers, particularly the warm and rich sounding Spendors. Play some saxophone and trumpet, or piano and string instruments such as violins, violas and cellos on both speakers and see which sound you prefer. All these instruments will sound very different through both designs. As to which is more accurate, that is up to one's listening preferences or expectations. If you attend live performances, you may be able to judge better.
Though I have to add that the Spendor S8e is not a very well-received model in the range when compared to the classic SP models, or the A series.
Though I have to add that the Spendor S8e is not a very well-received model in the range when compared to the classic SP models, or the A series.