I used 2 500w halide to start tomatoes this year before i built a 6500k fluorescent set up where they now live. The tomatoes germinated and continued to grow without a problem. I've got a couple tips for you.
Check the moisture levels often because the heat does evaporate the water fast with this light bulb. clear plastic tray covers are a must unless you want to be spraying the containers 5 times a day (which i did for the first few weeks). cut shape out of zip lock bag if you cant find anything more practical. When seedlings sprout, take cover away so they don't dampen off. This being said, make a new plastic tray cover with a hole where the plant comes out. this keeps the water in much longer (again, it took me a few weeks before trying this, but they stay moister, much longer).
Since the light gives heat, and not enough lumens (im not sure if this is true, how many lumens are you running?), transplanting them is finicky, so i prefer to plant one seed per pot to begin with instead of growing bulk in one container) transplanting them to their own pot later on. If nothing germinates, plant another seed in the dud pots. It takes a little more patience, but the stress from the high heat killed a couple during transplant.
My old system didn't push out enough lumens, so i wrapped cardboard in tin foil and enclosed the plant area to salvage as much light as possible. it also retained a bit of humidity which tomatoes love.
I'm interested to find out how large yours grow. I moved mine over to a florescent set up, and it almost seemed like the tomatoes were growing faster under the halide because of the heat.