Yes, you can move it to your current pension scheme, it happens all the time.
Disadvantage, you can't access the money from the old pot early if you want to without having to leave the pension scheme completely. It's not an issue for most people.
If the pension is reasonably small, you might as well transfer it.
If you keep it in a pension in own name, you carry all the costs, whereas your employer may be paying some of the costs in the scheme. If you do want to access the money early, you have to transfer to a Buy Out Bond, where you can access it from age 50. If you transfer to a PRSA, you can only access it from age 60 and still be working. You must have actually retired to access it from 50.
Steven
http://www.bluewaterfp.ie (www.bluewaterfp.ie)