1. you need to plan your usage of IVE before you use it. The maximum amount of ports and their performance are dependent on Multi Core Scaling value (MCS). To change the MCS you need to reboot the whole server. In a dynamic environment, where the amount of LPARs changes daily, you can’t daily recycle the power.
2. if you want to use SEA on top of IVE you will need to reserve the whole physical port for one LPAR. So the promiscous mode works on IVE. You don’t have anymore any advantages of virtualization.
3. if you’d like to use Etherchannel on one LPAR, all LPARs which connected to the same physical port of IVE, should also have Etherchannels.
4. you can’t dynamically add or remove VLANs on IVE port. You know, what it means, don’t you? 😉
5. and yes — as already Gremlin wrote, you need to stop the whole server, if you need to change your broken IVE.
6. earlier was also one more problem, but it seems to be fixed in the latest versions of AIX — IVE can be «etherchannelled» only with IVE.