it seems to me that a trip on the Rocket is one of those must do things.
Have done a lot of web searching including on this site and it appears that there are some conflicting stories about the need to book (most say it almost always booked out) and where it goes to from Dhaka.
I also found a post saying that prices went up by 40% earlier this year.
As this is a much asked question perhaps a sticky would be justified with all the latest info on this incredible journey.
Thanks and looking forward to info and comment on the Rocket