To data plan, or not to data plan?

My Nokia E71 (white, so pretty) has opened up whole new worlds to me. Things I've done with it so far:

1. Hooked up my 3 Gmail accounts to update whenever I'm around my home network.
2. Installed MSN.
3. Installed mIRC.
4. Installed the 'Go To' function on Nokia Maps.
5. Pimped it out with themes.

So now I'm deciding on the pros and cons of going with a data plan. Last month, my bill came to about RM10 less than it would have been if I signed up with a data plan. So I'm thinking, "isn't RM10 worth it to pay for unlimited access?"

Pros:

1. Unlimited internet access.
2. Realtime tweets.
3. Unlimited internet access.
4. Realtime emails.
5. Unlimited internet access.

Cons:

1. Unlimited internet access.
2. Realtime emails.
3. --- productivity

Sigh.