Seems the battery trays differ in pictures at the HPI site. In some pictures the sides are closed and in some they have holes.
Here's a pic with
no holes and here
with holes.
The BigSquid Savage seems to have these holes too, so I presume the production model comes with those. Whether it's good or bad remains to be seen.
There's a picture of an opened Flux tranny at RC Universe,
here.
I'm 100% positive that the transmission is straight fit to nitro models, but it's interesting to see that HPI has gone the easy way and kept the 2nd gear "pinion" at the input shaft (which is useless).
To my eye there's only one new gear at the tranny, all the other gears look like they're straight from the 2spd.
This ofcourse is proofed only when we can get hold of the exploded views & part numbers, so don't put your money on the line just because I'm telling so...
Now the diffs - the bevel & pinion gears do have their own HPI part number which differs from all the other Savage ones, including the XL's. Flux's gear number is #102246 and XL's #86248 according to the
HPI-Europe's Savage line-up (scroll down the page to comparison chart).
This obviously tells that the gears are (or atleast should) be stronger than in the XL.