There are so many elements at play here, however, if your experience mirrors what we published, maybe your friend has to re-evaluate his position There will always be different opinions on this subject, but ask 10 pros what their opinion is, and I would venture out to say that the consensus would be what I published on the article.

With that being said, there are so many variables that can create inconsistent results from car to car. My experiments were done with 2 identical cars, with identical geometries and the results gave us the conclusions we came up with.

Now, let's break down a few things, I am going to assume a few different things based on your signature.

1.Your Roche car is the transverse set up and your inline is the Speed Merchant.
2.I bet that the car that pushes is the SM car. Going to transverse, would definitely get your car to steer more going in and out of corners, but the biggest issue with the SM on lower bite tracks is the front end with no camber gain. With the different front end, you will probably have to attack set-up a little differently than on the other car since the car simply will not generate as much mechanical grip in the front. Typically the SM car will need a more aggressive saucing method in the front and/or a more aggressive front tire. Also, it will probably require quite a bit more camber to keep that contact patch up and gain the extra steering that it lacks. This should make a much bigger difference than simply moving the battery around.

I read the post that you linked to. That information is very lacking and to me, it seems like it was posted by someone who had little experience running that particular car at the time. If you read the following posts, a few guys were a little baffled by his conclusions. I would not put much stock into that information. The XTi originally was really aggressive, but I would attribute that to a really short center pivot to rear axle distance and if I recall correctly, pretty short side links. This makes the pod react very, very quick. The car was very fast, but it had a fairly narrow set-up window, which I believe is why the car's popularity was short lived and replaced soon after by the altered ego.