I gotta 133, but that's likely to stay at that level unless I do more 300 s, or ride extra distance on 200s, for no reason other than a bigger Eddington...
Nah, sod that 
I'd be better off riding more 600s, which would up the Edd, and I'd never get to the point when they ran out...
Damn right you wouldn't! As mentioned elsewhere E numbers are based on days not rides. An E (km) number of 600 would mean at least 600 days on which you rode at least 600 km !!! 
That's what makes it a bit iffy for audax riders. An audax riders' definition of day is a bit different from anyone else.
When I stick to the audax definition of day I have an imperial Eddington of 140, a metric of 202. Logging PBP, LEL etc. as 4 or 5 seperate dayrides, all well over 200km will of course give an Eddington of well over 150 (imperial)
I have the same problem as Ivo. As I haven't had a GPS then for most 400s, and all longer events I've no accurate figure of what was done up to 11:59:59pm and what was done after 12:00:00 - so I stuck to a definition of a single event (up to PBP, Mille Miglia) being one ride, but a multi-day trip (such as my trip to the Alps) being separate rides. Sir Arthur Eddington probably didn't consider this conundrum when establishing his rule. E-Numbers are 109 imperial, 156 metric counting muti-day Audaxes as one day and would be approximately 120 and 162 hazarding a guess at how the multi-day events split out. You can do Eddington numbers in any units - so a goal for 2016 is to reach E=500
furlongs (almost exactly 100km), although splitting multi-day Audaxes I would be fairly close to it already.
