If you check page 7 and page 9 in the Chinese product catalogue from Rigol,
https://www.google.no/?gws_rd=ssl#q=rigol.cn%2FFile%2FGuidAndView%2F%3F%3F%3F%3F_CN_201605.pdfyou can make the following observations:
When all 4 channels are used, DS4000 has 1 GS/s per channel, while DS4000E always has 2GS/s per channel.
When all 4 channels are used, DS4000 has 35 MPts per channel (140 MPts in total - shared for 4 channels), while the DS4000E series has 14MPts per channel.
Conclusion:
1) When all 4 channels are used, DS4000E has double the sample rate as the DS4000, but less than 50% of the memory depth.
2) When 2 channels are used, DS4000E has the same sample rate as the DS4000, but only 20% of the memory depth.
3) When 1 channel is used, DS4000E has half the sample rate as the DS4000, and only 10% of the memory depth.
So in terms of sample rate, the DS4000E series performs better than the DS4000 series when you use all 4 channels.