Unit 55 is controlled hunting only. You must draw a permit (except for a late archery hunt but I have not seen the 06 regulations.)
If you like seeing more hunters than deer, unit 56 is for you! Get there early for your campsite.
There are deer in both units, quality and quantity are relative to what you are used to. Since I have lived within a 45-75 minute drive of both units for 35+ years, my opinion is the hunting is pretty tough compared to 15 years ago. No surprise there.
I guess in summary they are where they are, you might get lucky in either of those units (assuming you draw 55)and smoke a great buck, but only with good preseason scouting or tremendous luck.
The 55 draw hunt is not really a "high demand" trophy hunt, it is a controlled hunt due to the units proximity to population centers of Burley and Twin Falls. It just won't support an open hunt. 56 was 2 pts only for 8 or 10 years but they opened it up to any buck 2 seasons ago. Sold something like 5000 tags for the unit in 2004. Got the heck shot out of it.
Good luck to ya.