| I don't pump yet, but am hoping to change that. In addition to what others have written, I would add the following bits that make pumping attractive vs MDI.
The newer-style basal insulins (Lantus and Levemir) are generally thought of as better than the older style as they have a much flatter response. The flatter response makes them more predictable and the lack of a peak does make management of BG easier.
There are problems with this, though. For a start, the length of time they last varies from patient to patient. Also, they DO peak. Not as violently as the older NPH but they are not 100% flat by any stretch of the imagination. Next problem is that the amount you inject seems to affect the absorbsion charactersistics. And the final problem is that, even if it did manage to stay 100% flat throughout the day and night, we all vary in our needs for basal insulin through the day and night so a flat response is a long way from what we actually need.
With a pump, you can (with experimentation) get it to match your basal needs in a far more accurate manner. If your basal insulin matches your basal needs, all of the other calculations that you must do on a daily basis have a much better chance of coming right.
You also have a far better chance of matching carbs to insulin due to the smaller delivery units. 1u of insulin drops me by around 2.5 UK numbers (47 US). If I start off with perfect blood glucose and eat a decent sized orange which has 24g of carbs. If my ratio is 1:10, I actually need 2.4U of insulin. I can do this on a pump. With MDI, I am left with a choice of injecting 2u of insulin and having a slightly raised BG as a result of too little insulin or I can whack in 3u and accept that I'll go a little low.
Gary  | 
