We will start a series on lights soon.
The thing with LED is, that you need sufficiently powered ones so that they can complement your lighting.
There is nothing wrong with using your old cans for the basic uplighting for example and then use some good LEDs to complement those.
American DJ has some awesome powerful lights these days and here are some good ones to look into:
Mega TRIPAR Profile:http://www.americandj.com/ProductDetails.aspx?Category=&ItemNumber=2085
Mega Go Bar 50: http://www.americandj.com/ProductDetails.aspx?Category=&ItemNumber=2124
Revo III: http://www.americandj.com/ProductDetails.aspx?Category=&ItemNumber=1728
Inno Color Beam 12: http://www.americandj.com/ProductDetails.aspx?Category=&ItemNumber=2136
They are reasonably priced and can really do some nice things for you and for LED have some nice output.