Any of the coils for the Explorer, the Explorer II, and the Quattro can all be used on the SE and vice versa. I don't think there would be any negative...if you like that coil better, than try it and see. I would only say that to me, it seems like the new slimline coil may be a little more sensitive, pinpoints very nicely, and is a little lighter than the 1050 coil. It would seem to be a no-brainer that you would rather have the SE coil.
I'm thinking the readings would remain the same. It does seem to me that the readings on the SE may be a little more granular than the II. For example, with the Explorer II it often seemed like a wheatie with a nice green patina or maybe an Indian would often come in with numbers very similar to a silver dime or quarter, like 00-28/29 and with the SE they come in more like in between a zinc and a silver. I expect this is the detector electronics doing this and not the coil, though I have not used a coil from the Quattro or the Explorer II on my SE.