Used the Union Force for a while and I have to agree one of the most responsive bindings I've used. I like them a lot but stopped using them a year ago and then sold them. Responsive yes, but the straps sucked so bad I got sick and tired of wrenching them off at the end of the run not to mention shredded two pairs of gloves in the process also. If Union would fix the strap issues they would be perfect. But light weight? I don't think so, compare these to either my Contacts or my 390 Boss and they are heavy. I think the Contact weighed less, responded just as good as the Force and were even more comfortable.
I liked the Union Force but if they would just fix the straps I would deal with the added weight of the full length base plates. On a side note Union has the best sole length adjustment on the market for bindings. Very easy to get an absolute perfect center for your boots on the base plates.