Thought to share my cock-up in the hope it will prevent someone else making the same mistake. Here's the mistake I made: contrary to the instructions for bottling to add the provided dextrose after syphoning into the bottling bucket, I decided to syphon the beer onto the dextrose assuming it would gradually dissolve and spread evenly with the beer.
Well, by the end of the bottling the residue at the bottom already gave me a clue this had not happened completely; there was some dextrose left at the bottom. So, as you can imagine, the first bottles are under-primed, which means.....the last bottles are over-primed! To date, I have opened one gusher and had one bottle bomb.
As a safety precaution I put them all into the fridge to stop any further bottle conditioning. Just opened another one, that is under-carbonated. Sadly, I have no clue which bottles were first and which ones last.
So, as an advice, follow the instructions on this one to stir in the dextrose and not, like me, worry about oxidation this may cause (or better still, do the usual routine to dissolve the dextrose in boiling water first and syphon the beer onto that).
Other than that (even without the carbonation), this is great stuff!