Ed - There's a couple of Key differences between FlightPower and OptiPower that have been noted above.

FlightPower is a company, run and distributed in China with no UK distributer or warehouse (this was a new thing that wasn't made obvious when they moved).
OptiPower is a brand of a UK based company, with many many top re-seller's in the UK and Europe.
The company behind OptiPower/OptiFuel brand is PMA (Process measurement and Analysis), a multi million ££ chemical company that's based in Huddersfield. This is where they manufacture all of their fuel and where all their lithium packs are tested and distributed.

Because of this, all orders are taken by PMA, which means someone's always there to answer you calls!

Ontop of that, Andrew the owner is very active on the RC circuit (it's his hobby too) and is at almost every major event on hand for help and support. Julian Cox from FlightPower has not been seen at an event for quite some time.

Read up online and you will find the feedback excellent.

With regards to the FRA's second opinion, through out the process I was in discussions with Kane about this, however at the end of the day the decision is best laid down by myself as I have by far the most experience in this field (been using lipo's in robots alone since 2006 UK champs). Sadly FlightPower was an exception where the whole business had moved and things rapidly changed around the same time.
I know Andrew personally after flying for his company for years and he genuinely is someone you can trust.

But at the end of the day it's upto you