M12 vs M18 V5 inductive probe I currently have my printrbot with a LJ12A3-4-Z/BX-5V Inductive Proximity Sensor ( 61mm M12 DC 5V NPN NO 300mA)

That detects my aluminium bed at around 1.2&nbsp;mm distance. While it works, if the printer does the smallest blob the probe crashes into it. 

I am considering replacing the probe by the M18 version LJ18A3-8-Z/BX-5V (
M18 8mm DC 5V NPN NO 300mA). 

I haven't been able to find real specs for these probes (apart from what the sellers put in eBay or AliExpress - which I do not trust). 

Will I get a larger detection distance with the M18 version of the 5&nbsp;V probe? (I wonder if the M18 version is exactly the same M12 version with a larger casing).

Or should I move to the 6-36&nbsp;V versions of the probes - I do not want to do that to not modify my wiring.
The larger the diameter and the higher the voltage the larger the detection distance. You do not need to do much wire modification if you use an optocoupler, see this anwer.