Diesels tried and tested
Well, in the end I bought one of Henry Price's diesels, the 456cc one with a '13hp' engine, and 18litre tank, and a rack. On the 150 miles journey home the rear tyre blew out on the motorway due to sharp metal edges on the rim at the hole for the valve that hadn't been de-burred. 2.5 hours for recovery, and 2 hours labour to fix, and £15ish for new michellin tube and rim tape.
On the two journey I made to work it struggled to do 50mph, and could only manage 30mph up hills.
At 500 miles the crank snapped whilst at 40mpg in town. 3.5 hour wait for recovery, then a 2.5 hour journey home. Henry picked up the bike and returned it a week later, fixed.
New engine a little better and could manage said hills at about 38mph in top, whilst top speed when pushed was 55ish, but cruised at 50 to be safe.
At 1450 mile the rotor shear the bolts holding it onto the flywheel and began spinning loose on the crank. 4 hour wait for recovery (due to phone breaking, pay phone not working, pub not having a phone, and locals not letting me use house phone. Engine fired up and a very scary and noisey journey made to next village a mile down road. Found wonderful pub who let me use phone, and had home made pie and chip & 2 drinks while I waited. For just £9!) then 2 hour journey home. Bike taken off road, and returned to Henry for refund under sale of goods act, which took 2 months, but eventually went through amicably.
With respect to Henry, he did apologise and issue me a fair refund, just a shame about the crap chinese engine. The 40 year old bike itself was about the only thing that worked funnily.
Not back on ER6N, which has now done 33,000 miles in 14 months, less a few weeks on the enfield. Serviced roughly every 10k for about £300 and new tyres, chain and pads roughly every 8-9k at about £350 all in. Problems with bike: rear wheel bearing went at 20k. Cost: £17.50 fitted to loose wheel. Bike still looks as good as new and is on MCN for sale at £2600. Am aiming to get a Ducati 999. Don't ask...
Verdict: Kawasaki 1, Enfield Nil.