Of course, the atmosphere is different, because the House of Commons is
purposely constructed so that there isn't room for all the members to
sit down at one time and so that the two sets of benches face each
other rather than the speaker. In these more crowded and
confrontational conditions, which would not apply in the comparatively
decorous surroundings of the Capitol...
From a purely practical perspective, how would this work? In the House of Commons, the opposing parties literally sit only a few feet apart. Indeed, the physical configuration of the House of Commons has been compared to a football pitch, which of course speaks to the proposed usage of said chamber. What would members of Congress do, shout their questions at the president? Or perhaps we'd have someone running around with a mic a la Oprah Winfrey.
Don't get me wrong, I'd love to see any president receive the what-for during a "president's question time." As with all trial balloons floated by the candidates, though, a little more detail about how it would actually work would be welcome.