I'd jump over a teralow kit to get to the factory 241 0R, and deal with the size and speedo issues. Put them side by side, and I would not hesitate for a second, everytime I'd choose the same, the 241 0R. That's just me. I looked into this a little while back and factored in the price of the teralow, the fact that the kit is expensive, does not come with an sye, unless maybe you option for one on a whole case, the 231 case is not as good as the 241. if you have a teralow kit, great. But, there is no denying in my mind the 241 is a superior case. That's just me. I am not disagreeing that both have proven, but, again, factor in what you can get a good 241 0R for price-wise, and the end pricing in a teralow setup..and which is better as an end result on top of that. Bottom line, the 241 is better, and will probably be cheaper as an end result.
If you are really considering this..I would also strongly consider jumping over both those options and go for a Dana 300 with a flip kit. Its shorter by approx 4 inches than either of the above cases even with an sye, and its a twin stick, gear to gear reduction case, and competitively priced, and you can get a speedo adapter with that setup. The Dana 300 is one of the best cases ever made.