When looking at an engine's compression keep in mind that is the static compression. As GMs cam profiles have been getting more race spec - the dynamic compression isn't as high as one would think. Point in case, the LS2 (10.9 static compression)is able to take 10psi and make a cool 600whp as proven by APS.
Nitrous will make more power but works in somewhat of a two fold. Generally the piston and rings have a cooling affect, where as boost tends to get them really hot. It seems that nitrous, in the long run, can be harsh on bottom ends when you really start cranking up the juice.
As others have said nitrous will create more power for less money.
If you plan to road race, you might find a centrifugal supercharger easier to deal with as it keeps predictable pedal feel and drive-ability of an NA engine.
One thing for turbos - if they are sized correctly they provide a relatively quick, but not to quick change in torque. With nitrous, as soon as it comes on, torque goes through the roof in a very short time period. A progressive setup would probably fix that, but naturally turbos offer slower torque transitions.
Just some things to think about.