I own a double-braced stand, but would not recommend it for an 88-key instrument - even with my 76-key board, there is quite a bit of a wobble, especially when I play at either end of the scale. This type of stand feels even more unstable if you play standing up - you make it taller by moving the legs closer together, thus giving up stability.

If I were buying another stand, I would go for a platform stand, such as http://www.zzounds.com/item--MUPKS7100 - it is only $30 at Musicians' friend http://www.musiciansfriend.com/srs7/g=key/search/detail/base_pid/450384/
or a stand like this one: http://www.zzounds.com/item--QLKWS550

Another stand which I thought was really neat and easy to transport was the On-Stage Z-stand, also available as a single tier: http://www.musiciansfriend.com/srs7/g=key/search/detail/base_pid/450389/

Also, some people here really like the Quick lock stand like this one: http://www.musiciansfriend.com/srs7/g=key/search/detail/base_pid/450048/

Some people in this forum really like their X-style stands, and particularly the ability to hang a bag with accessories between the horisontal bars; however, with a large and heavy instrument you have to pay particular attention to stability.

Good luck,

Alex