I wouldn't say it is a "problem" with the not having POE feature and running a separate power supply for most situations wouldn't be a problem.
The DS-2DF8836IX-AEL(W) would be in a different league to the NEW Dahua I would think ask Parley he has a Dahua with a 2/3 sensor and can be had on eBay Uk as a demo model for less than 1k
I would ALWAYS take a 2/3 sensor no matter what the sensitivity is over a 1/1.8" or 1/2.8" sensor and out the 3 mentioned above I would still go for the DS-2DF8836IX-AEL(W) for my situation and environment , your needs might be different.
Price difference I have no control over sorry but I know it is VERY expensive to send or receive parcels now from over the pond as my cousin now lives in Houston Texas.