Sorry - this is not quite correct. When you export the to SSIS - the type of package is still defined as a maintenance plan. If you then open the package in BIDS, change the connection information (not the name) and perform a Save Copy As - you can place the package in the Maintenance Plan folder and it will still be a maintenance plan.

However, you have to also modify a setting in BIDS (which I cannot remember - since I haven't done it in a long time) to reset the GUID and other identifying information. If you do not make that change, the package runs - but will report failure even if all tasks are successful.

I find it is just easier to spend the time creating the plan - which doesn't take very long and is not something I do on a regular basis anyways.