Although you have a tank thats large enough to keep a Palembang with plenty of space to spare, i'd be a little worried about it picking on its tank mates... especially since Palembangs are actual Piscivores and not nearly as friendly as an MBU is...
Personally i've tried keeping my palembangs with other smaller fish or fish of the same size and most of them ended up being eaten over a period of time or killed...
Anyway, overall as i see it, even though they are lurkers who seem to be lazy and slow, when they want to move they can move real quick... so i guess those are just a few things for you to consider before jumping the gun and getting one for one of your other tanks...