Interchangeable Implements of Destruction

[Rush <jdrush@enter.net>]

My string trimmer and my hedge trimmer both died in the same week. :( I 
see some lawn and garden devices with a single power unit and 
interchangeable accessories.
http://www.echo-usa.com/prods_list.asp?Category=PROATTACH
http://www.kawpowr.com/handhelds/accessories.asp
http://www.stihlusa.com/multitask/index.html
Anybody tried these? Are they gimmicky or good? Who's do you think is 
the best?

Jon