I agree with everything Howsie and 666 SKY have said.
My comments apply to a lightly modded EVO VI (maybe 320 bhp, versus a circa 380bhp R33).
Generally the Skyline will be slower over tight B roads (especially wet ones), but generally quicker in most other circumstances. This is a function of its size and my driving abilities (ie not being good enough to "slide" around corners).
The skyline is easier to drive, both in traffic (because of the skyline's more progressive power delivery as opposed to the EVO's on/off type delivery) and on the motorway.
The evo feels frantic, particularly in 1st and 2nd gear and losses some urge in 3rd. The skyline revs higher and keeps going in every gear. I think this generally gives it a significantly better 0-100 time than the EVO, but a marginally better 0-60 time. The skyline's in-gear times feel significantly quicker.
I find the skyline much more rewarding to drive than an EVO VI, although I would prefer the VI for certain limited situations eg the wet b roads. I think both cars ride very hard, particularly when pottering around - in fact the evo possibly has the edge here.
I have had no reliability problems and follow the standard service schedules (6K miles or 6 months), and have found the costs of running the skyline to be similar to the EVO.
Hope this helps.
By the way what are the details of your EVO - I feel I have to buy a Tommi Mak version at some point in life.