In terms of price performance MAC AIR definitely is better deal than iPad2.
iPad2 is just an expensive toy, will be outdated every 12-18 months. Mac Air got 4GB RAM and large HD(minimum 64GB SSD), and much powerful/capabile CPU. The lowest configuration is only around $900, it will last 3-5 years without upgrading hardware.
There will be no issue about flash and jailbreak.