Advice on deciding between 250/250 or 500/500 flash kit

[Ineedhelp]

I could use a little advice on buying a lighting kit.

I am looking at the Bowens Gemini two head kits that include stands, an umberella, a softbox, reflector, cables etc. They are described as having a 5 stop range and I could get two 250W heads or two 500W heads, pricewise there's not much difference.

I would intend to use them with my 350D (Canon 50 1.4, Canon 85 1.8 and Tamron 28-75 2.8 lenses), mostly for portraiture. Would also like to take pictures of pets but I guess those sorts of flash might be a little scarier than on-camera flash!

I am a total hobbyist and will almost certainly use them in the home or slightly larger garage. Any thoughts on Bowens as a maker or more likely whether there is much advantage to shelling out for the more powerful 500W kit?

Thanks