Diels was definitively a friend of Epicurean Philosophy.
Presuming you are right about that (and I have no reason to doubt!) then it would be really interesting to read Diels' commentaries on Lucretius in particular or Epicurus in general. Anyone who spends the time to translate the entire poem has to be dedicated. There's a great deal of interesting commentary in Munro's translation, and the same thing for Bailey (although I don't trust Bailey's views as much as I trust Monroe's).
Do you think any of that is available?
I wonder if it would be worth going from German to English to pick up any twists that Diels might have seen in some of the key passages, such as around line 62 in book one. Is it worth a look to try to track things like this down:
Humana ante oculos foede cum vita iaceret 62
in terris oppressa gravi sub religione,
quae caput a caeli regionibus ostendebat
horribili super aspectu mortalibus instans, 65
primum Graius homo mortalis tollere contra
est oculos ausus primusque obsistere contra;
quem neque fama deum nec fulmina nec minitanti
murmure compressit caelum, sed eo magis acrem
inritat animi virtutem, effringere ut arta 70
naturae primus portarum claustra cupiret.
ergo vivida vis animi pervicit et extra
processit longe flammantia moenia mundi
atque omne immensum peragravit mente animoque,
unde refert nobis victor quid possit oriri, 75
quid nequeat, finita potestas denique cuique
qua nam sit ratione atque alte terminus haerens.
quare religio pedibus subiecta vicissim
opteritur, nos exaequat victoria caelo.