I was in your exact spot half a month ago and decided to go with the Sigelei. Still in the mail though so i can't comment, but i can pretty much sum everything i've read here:
1.) They are the same chip and the same device.
2.) Ipv Mini has a history of paint peeling
3.) Sigelei comes with a silicone shirt
4.) Ipv mini is more "ergonomic" while sig is just a.. well a box.
5.) Only point 1 is really important. Take the mod you think looks and feels better for you.
Oh and i should add, i greatly prefer the battery door of the Sig
