Summit on 4S, help me choose the right motor for the RX8 system!

[RCPao]

Hi all, I have a Stampede VXL and an E-Maxx BL (IMO brushless is the only way to go and one of the main reasons I got back into the hobby a couple of years ago).

Now, I have just got a Summit, I have it since 2 days, and I am of course going to put a BL set in it ASAP (the truck is a lot of fun but the stock performances are a joke).

To explain what I am looking for it's probably best to describe how I use my E-Maxx because use will be similar.
I have in it a Mamba Monster 2200KV Combo and I always and only run it on 4S lipos (I have two SPC 8000 2S and four Turnigy 5000 2S, I am going to buy some more 2S lipo BTW).
I run 95% of the time offroad in the most diverse conditions and do pretty much everything with it except long runs at or near top speed.

Frankly it would be easier and cheaper to just go with another MMM, I even already have the CastleLink, but given the nature of the Summit I think it practically "must" have a sensored BL system!

So, given the above, which RX8 motor should I get? The choices are maybe even "too many"! :D

The big real question is: which version (KV) works best for me??
Bearing in mind that I only run 4S, I am not interested in very high speed (but on open field still like a bit of WOT), I like torque, I drive almost only offroad and sometimes in very hard conditions which one works best for me? Under the mentioned premises which will be the most efficient (i.e. lower temps, longer runtimes) but still plenty powerful and fun? 2000 or 1700?? (I have already ruled out the 2250KV and, obviously, the 1550 and 1350)

TIA!


P.S. Has somebody any idea about how top speed would compare between stock and the 1700KV with stock gear ratio?