i was looking for a better headlamp for night riding on the country lanes and noticed that bandit and sv650 head lamps look like this:

http://www.ebay.co.uk/itm/HEADLIGHT-HEADLIGHT-SUZUKI-SV-650-1999-2000-2001-2002-/281737090502?hash=item4198d6d5c6:g:s0cAAOSw-vlVkrTu

anyone know if its much of an improvement ?

cheers! 

Since the bulbs on both of those headlights are interchangeable and you aren't modifying the wiring of your bike I predict that there will be practically zero change in performance.

This would pretty much just be a change of the housing.

You could look at LED headlights and get more light output.  Other options include HID lights or upgrading the wiring to the headlight to minimize the electrical resistance.