Good question.
Being an independent builder, I get the opportunity to build with all of the mfg parts, depending on customer preference.
The Reid one piece is the bench mark of the after market cases, it's a great case with no problems installing parts in them. Their 2 piece case is of the same quality and with the bell housings offered it makes for a cleaner install when going with Ford or Chrysler applications. I have always liked their products. The cost how ever is on the high side of the market.
I have 2 customers that have the ATI 2 piece super case, Both of these were brought to me new for me to move their parts into. The first went great, the second on not so great, I had to do some work in the park paw pivot pin area to get the pin in the case and the clip on it, this costumer also brought in an ATI super servo. This did not fit in their case and would not fit in a stock case, this told me the problem was with the servo after machining .008 off the OD that goes in the servo bore we were in business. The cost of these cases are on the high side of the market also.
JW where to start. I have several customers with JW Cases and Bells, or just the bells on a stock case. The cases are very heavy and the bolt thru the pump design is not the best. I have had to massage 2 of these cases just to get the reverse pressure plate in, and these things are almost impossible to get not to leak it's more so with just a bell to a stock case, but they still are prone to leaks. With bell twisting on the pump bolts under torsional forces of the chassis, this causes the pump to shift in the case resulting in some leakage, not major leakage, but if your like me I hate drips in my trailer. The cost of this set up is in line with other 2 piece case set-ups, but the weight, bolt thru pump design, and the leakage issues are the problems.
I have used a lot of Transpecialties cases, and have one of the original run of 10 cases in my Roadster. Like the Reid case I have never had any issue with fit or quality with their products, and at PRI they showed their new 2 piece case, it is under going the SFI process to be approved for sale. it is a bolt to case design like Reid and ATI, and I expect the quality to be as good as their one piece. Their pricing is mid range compared to the other mfgs.
BTE I saved them for last for a reason. I pulled my records and I have 9 customers with the BTE one piece case, (which is not offered any more as they went back to using the Reid in their builds) These cases were horrible, requiring a variety of different things to make them usable, from removal of cast flashing, massaging the case for reverse pressure plate fit, honing the servo pin bore to get the servo to fit,to tapping holes that were left un-tapped. They are now offering a 2 piece design, I hope the quality of this case is better than their other was, looking at the case at PRI it looked good but until you start installing parts you won't know, and I have not used one yet so I have no experience with them. Again I hope they turn out good, cause they are price right.
This are only my experiences with these products, and others my have other opinions. For the record I am a Transpecialties dealer, but I believe I have not shown bias in my review of the cases. As stated I have a TSI case in my Roadster, but I have a Reid in my Camaro.
Thanks for the question and for reading,
Dan