pelikan tail.. why no es bueno?

based on a thread here

i noticed that many companies attempted a pelikan tail but opted against it going to a conventional 4 tail solution. so far the only problem cited is weight but it seems the advantages are high.. especially in the stealth aspect

for example:

McD’s JAST started with a pelikan tail

later switched to a conventional tail

Boink started with a pelikan tail
http://www.secretprojects.co.uk/forum/index.php/topic,2121.msg18031.html#msg18031

later switched to a conventional tail