Cassette difference

[Nozzer]

Quick one, im using a shim 105 12-27 cassette, would i see much difference with a ultegra 11-28?
Would the extra 1 each end make much difference? Also, would any adjustments need to be made?

 

[RecordAceFromNew]

I assume they have the same number of sprockets. Adjustment is very unlikely to be needed. You will find changing to the 11 noticeable since it makes your highest gear at the back about 8% higher, and the 27 now being a 28 will be less noticeable since the lowest is now going to be lowered by less than 4%. Imho you are unlikely to notice whether it is a 105 or Ultegra.