I hadn't realised there was a difference between the 'P7' and the 'T6' - they all lok the same to me!
My single LED light is a P7 - quite 'spotty' but very good range - therefore ideal for helmet.
My triple LED bar mounted light is a '3 x CREE XML T6' from Amazon. It doesn't quite have the range of the single, even on full power, but the flood of light is quite remarkable.
Put these two lights together and you have (what I think is) the perfect combination.
On the subject of pricing, I could live with a premium of as high as 50%-60% over and above 'cheapest on the internet', but not 300%-400%.
For example - I bought my dropper post from R53 Sport for about £120, but I'm told I could have got one on the web for £80. I took the view that £40 on £80 was a price worth paying for a warranty and 'local' back up if I need any spares.
When you get into lights, though, my 3 x CREE is basically an unbranded Gemini (I think) with a less premium -brand battery. The Gemini retails at over £180, I got mine for £40. So, assuming it doesn't burn my house down whilst charging, £140 on £40 doesn't seem reasonable for a bit of back up and spares.
mtbbatteries.co.uk seem to be a reasonable place to go as they are pretty honest when they say the lights are available cheaper elsewhere, but you are paying a premium for their service. I opted not to, but that's my choice.
The big brands are just taking the mick, I'm afraid. A bit of fancy laser-etching and a slightly better battery do not justify a 300%-400% mark up!