[Mr Gazza]

Mmm! going back to the plugs, They are going to be pretty much all that was changed in the pre-tantrum service that would effect starting.
New plugs doesn't mean good plugs necessarily. I've recently bought a few plugs for a new rebuild and I'm now on the 3rd pair in the first 300 miles having found that they fail alarmingly quickly. The gaps always need checking from new as they are quite random out of the box. Granted I had other issues with the ignition system as well as the plugs but they did manifest a hot starting problem, with cool plugs seeming to make a better spark.
Are they the correct grade NGK plugs?

My Motobatt on the Monster is still going strong into it's tenth year but it's worth doing a voltage drop test by putting a meter across the terminals and seeing what the voltage goes down to when cranking.
Strange though as it's usually under more duress when starting cold?