I owned a B7500 for a couple years, thought I would need a block heater, but never got around to installing it. I NEVER had a problem starting the B7500. It was stored in a machine shed up here in Wisconsin. Several days below zero...etc..
I would definitely recommend the Kubota block heater. It does make a BIG difference in cold weather. My BX2200 will start when it's cold but it is much smoother when the heater is used and engine warm up time is reduced practically to nothing. The temp gauge starts climbing almost immediately. You should still let it run for a few minutes to warm the hydraulic fluid some before heavy use. They claim it will also give your diesel longevity. For the cost of these diesels it is well worth the price of a block heater in cold climates to get all you can get from them. Once they are installed you never know they are there until you need to plug them in. Wouldn't be without one on a diesel. /w3tcompact/icons/smile.gif