After careful consideration, I have decided to reject this map removal.
I want to sincerely thank everyone who took the time to weigh in on this vote. Due to several thorough and drawn-out opinions in this thread, the pros and cons of this map are crystal clear to me. Shit, I feel as if this thread turned into a metacritic review page for just 1 JailBreak map (goto metacritic.com if you don't know what I'm talking about).
The conclusion I will draw here is yes, this is a flawed map; it's a map that could be even better if the creator updated it out of beta. However, in its current state, it seems that this map also has a niche on our JailBreak server, which I believe is proven by its popularity (even if you factor in the 'vote 4 every time' votes) and the results of this map removal poll, which is almost split down the middle.
I feel this quote by @LukeN best describes this niche:
Spy_vs_spy is definitely one of the more simpler maps in the map list, it's straight-forward, small, and it slightly favors CTs in comparison to the majority of JB maps which favor T; so I can definitely see this map as being the most CT noob friendly in our arsenal and just noob friendly overall because it's a lot easier to wrap your head around everything that is going on (which also makes it an easier map to admin on). It's also unique in that there's no other maps like it.
It's honestly difficult for me to remove a map that is very popular and with no similar maps to substitute it. If another map removal thread is made in the future with more support to remove, we'll revisit this. Until then, the niche will stay.