On the contrary, an ACEA E6 oil might be expected to be more damaging to a DPF.
Firstly, the capability of the oil to handle soot in the engine has no bearing on soot in the exhaust gas stream. All it means is the ability of the oil to disperse soot and mitigate its effects (thickening, abrasive wear) once it has entered the oil.
ACEA E6 is a 'low SAPS' specification in the context of heavy duty engine oils. However, compared to car engine oils it is actually of a full SAPS type, hence it would be likely to block a DPF with ash more quickly.
In the car world, ACEA C2 & C3 (and the associated OEM specs like VW 504/507, BMW LL-04, MB 229.31/51 etc) have a maximum ash level of 0.8 %wt (typically referred to as "mid SAPS"). ACEA C1 and C4 have a maximum ash of 0.5 %wt ("low SAPS"). The ACEA A/B specs are all higher than 0.9 % wt, with A5/B5 going up to 1.6% wt.
On the other hand, ACEA E6 has a maximum ash of 1.0 %wt (so 25% more than ACEA C2/C3). This means that up to 25% more ash could be flowing down your exhaust and into the DPF (not taking into account any effects due to viscosity, volatility, engine appetite etc).