First, my personal opinion is that I prefer PS3 engines over PS2 engines for a variety of reasons, including:
- Rule 17 lighting,
- Truly operational rear ditch lights
- The realistic look of the wireless drawbar. Even with mild arthritis in my hands and issues from an injury several years ago, I find no hassle to connect and disconnect the drawbar
- The use of Supertcaps instead of batteries
- The ability to update an engine's firmware
- The very much improved signal strength (FPGA chip instead of ASIC for the DSP)
- Continuously improving details on both Rail King Imperial and premier engines.
From a repair standpoint, I don't like the very small gauge wires used inside the engines, particularly in combination with the "notorious" 40-pin connector. However, unless you do your own repairs, this is of little or no consequence.
There have been issues with PS3 engine firmware, wire routing and lovely blackened screws. However, the firmware was designed to be upgradeable and the other two issues should be rarer as production methods clean up these "teething pains".
Second, while I also have seen issues with PS2 5 volt engines, I've never had a board fail in an engine that I bought new, that wasn't my own fault. While I've had a couple that I bought used that soon failed, I have no idea if they were mishandled by their previous owners. The newer 8.4 NiMH batteries I use as replacements seem to fare quite a bit better than the original NiCads that they replaced.
I have replaced a score of 5 volt speakers (early ones were often defective), however, that's typically an easy fix.
Now that I have my "rant" out of the way, I have some small bit of information to share as regards MTH Triplex engines.
I own an original Rail King Imperial Triplex. It's a very detailed model with a 3 volt PS2 board. It's been a fine performer and is, in my opinion, a terrific-looking engine. I would highly recommend it or its newer 3 volt sibling.