insert_batch performance and limitations??

[eluser]sotoz[/eluser]
Hello everybody!
I'm writing an application that sends sms and I'm keeping (obviously) a copy of the message on the database. Till now, for prototyping purposes, I was inserting each message into the database one by one, but for bulk sending messages I will use insert_batch to fasten the whole process. I'm talking about 1000-5000, and maybe more, sms (inserts) per user request at one time.

My question is, is insert_batch going to be sufficient, fast enough and bug free to such big amount of inserts? Or is it being used for less inserts per batch job. Is it safer or faster to make a custom query with multiple rows in one INSERT? Are there any limitation on the amount of rows that can be inserted with insert_batch?

Thank you in advance.
I will keep you informed of my progress with that for anyone that cares.
Sotiris