hold on!
I may be putting 2 and 2 together here, and getting 5, But!
Im an active member on the US Traxxas forum, And a few people have been getting their new E Revo brushless editions with the new Traxxas2.4 GHZ LINK System (As opposed to the regular 2.4 GHZ)
I didnt know what this was, So Checked their site:
http://www.traxxas.com/products/accessories/traxxaslink_24ghz/traxxaslink_overview.htm
It says in that text
"Traxxas introduces the next generation of 2.4GHz radio system performance and it's available now in the new Traxxas Slash 4X4."
AS far as I am aware, The Slash 4x4 always came with the 2.4ghz, But not the Link 2,4ghz?
A quick check on modelsport and Quite a few Traxxas models have gone up in price:
Now look on www.traxxas.com
Top right a big square with new info on the TQ 2.4ghz system.
My hunch (which doesnt explain the Summit price hike):
Models that came with the 27mhz now come with the TQ2.4ghz
Models that came with thw TQ2.4GHZ now come with the TQ 2.4GHZ Link
Could be wrong however!