I vote with the rest.
Keep in mind that if you are in a weight range that overlaps go with the more substantial axle. The increased wall thickness of the square tube will come in later on as an added benefit.
Take a look at the thread below:
Check out posts # 44,49, and 53.
I went with the #11 Dexters with the rubber cut down (3600 lbs per axle).
I contacted about four or five torsion axle manufacturers and none would warranty the axle more than 5 years. In a previous life I worked for a small offshore oil producing company, the large reciprocating engine vibrations were dampened by mounting the engines on a large cantilever, sort of like a huge tuning fork, and thick rubber sheets were utilized as a damper to limit the cycle severity - learned a lot about rubber life under compression.
I also went with the 45 degree start angle. I'm glad I did since it really increased my clearance all around. I would be more than happy to field individual questions.