Doesn't seem to be any big conspiracy. Just looks like an updated AMBrc3 decoder, that can read the new transponders..... even says the AMBrc3 can be turned into an AMBrc4 with a firmware upgrade. So the decoder hasn't changed at all.

The transponders are being updated. They fixed a few problems.... not scoring reliably with four cell NiMH or one cell lipo, smaller size to match competitors, and an added digit to have enough numbers available.

Only problem I can see is if someone shows up at a race with the 8 digit hybrid, and it matches an AMBrc2 7 digit PT number, and the club has the AMBrc2 decoder that can't tell the difference. The chances of that are a million to one.

Clearly from the PDF:

....."MYLAPS RC4 Hybrid Transponder:

Can be used everywhere
• Works on RC2, RC3 and RC4 Decoders


RC4 Decoders are fully backwards compatible with current MYLAPS RC2 Transponder (formerly known as AMBrc-
DP transponder) ....."

So, new RC4 transponders will read on all systems (7 out of 8 digits on the AMBrc units)

and, the AMBrc4 decoders will pick up current and hybrid transponders....