I was speaking to my dealer about this just the other day (for my TC33D), asking about Woods 7500 and NH 757C backhoes. His statement was: With the BH installed, you definitely have less ground clearance. With it removed, all that is left is a couple of brackets. He said that these are very stout, and oriented in the direction of travel, so if they do become an issue, they tend to slice through the ground, rather than "shovel" through it. He also said that since the brackets are out to the sides, near your tire tracks, it is less of an issue... you still have decent clearance in the middle (he owns a TC45D, and has at least used a NH BH on it, not sure if he owns the BH or borrowed it).
John Mc