Hi Quagmyre
It all depends on what you know about Spitfires. If you are satisfied with a model that looks like a Spitfire to you, then the Hasegawa is the easier build. But if you want a Spitfire to scale, then the ICM is much better. The Hasegawa is too short in the fuselage so Hasegawa thought that they would fool everyone and bring it to the correct overall length by making the spinner way oversize. When done, it looks totally ridiculous but some people wouldn't know the difference. The ICM is a bit more of a challenge to build and initially they had a Quality Control problem with short shots, sink holes etc. That has been pretty well solved now except for a sink mark just forward of the ailerons on the upper wing surfaces.
Here is a photo of the Hasegawa IX nose to nose with the ICM.
Notice the size of the spinner on the Hasegawa on the left. The ICM has the bulged upper cowl and the Hasegawa doesn't.
As for doing a Spitfire opened up, well the ICM Merlin given in the kit doesn't look too much like the real thing. It really lacks the intercooler behind the cylinders. ICM has it there but it is very small. I did two build articles on the ICM Spitfires over on HyperScale. The one on the Mk IX was the first one that I built
http://www.kitparade.com/features00/spitfireixconstructionrs_1.htm
Later I did a Mk VII which you may find interesting too. In it I walk you right through building an ICM Spitfire.
http://www.features02.kitparade.com/spitfireviicbs_1.htm
In the first build I found out that the ICM Merlin will not fit under the cowlings.
Cheers
Bob S.
Oh yeah, The Spitfire was in the Pacific too. In fact it was in all the theaters of WWII.