Differential pairs have more noise than a single ended design, which is
why the transformer is the way to go. An ideal transformer has no
noise. I real life transformer has the noise of the resistance in the
windings. This is why the transformer choice isn't trivial.

If you buffer (source follow) then use an amplifier, the noise of the
source follower gets amplified. This is why you wouldn't normally do
any buffering before amplification if low noise was the issue. However,
in the case of a tuned loop, you need the high impedance to keep the Q
high. Wellbrook gets around that problem by using a loop that is not
tuned. The assumption is the purchaser has a real radio and doesn't
need front end filtering. So cource having a high dynamic range like
the 7030 is a plus.

Loops using ferrite will not work as well as a Wellbrook IF the
Wellbrook uses a large enough loop. What you are gaining with the
Wellbrook is aperture. It soaks up lots of RF due to it's size.