if you go higher than 5.1, u'll need bigger space...

if space is restricted, the panning and sound separation can't be heard clearly, so pointless to have...

and due to that, not all dvd titles are mixed with 6.1 DD surround-ex since 5.1 are sometimes more than enough

btw - matrixed sound won't give the same effect as discrete surround...not advisable to use that...but try it firstlah, see whether ur gonna like it or nit,