I've used breakout boxes for various things, but, assuming that it's really RS232 on either side, the Smart Cable wins each time. The cheaper one fixes most things (that is, swapped TX/RX and swapped DTS/RTS, IIRC) with two toggle switches indicated by two LEDs. It's very simple. A monkey could do it in seconds. The more expensive one can be used to do pretty much anything that you'd reasonably want to do with a breakout box, again, assuming that it's RS232. If you've got some bizarre pinout, though, a breakout box is invaluable.