The only advice I would give to anyone who needed to know is that CTRMA toll road shields have a yellow border and Clearview digits, but TxDOT uses a white border with FHWA.
The RMAs were created in the early 2000's when the Texas Legislature punted on raising fuel taxes and I believe at least three--CTRMA, HCRMA, and CCRMA--now either operate toll facilities or have them under construction. They exist alongside county and regional toll authorities.
CTRMA, NTTA, CCRMA, HCRMA, and TxDOT Turnpike Division are using variants of the same shield design that looks like a double-hung window. The top rectangle has the route number or acronymized facility designation, inside an elongated version of the appropriate shield if the facility counts as part of a US or Interstate route. The bottom part has a rendering of the word "toll" and a logo that may be agency-specific. For NTTA this is the TollTag logo; for CTRMA it is a road-into-star design; for CCRMA, HCRMA, and TxDOT Turnpike Division it is the Lone Star flag.
The latter version is in
SHSD and I believe it is available for use by any agency in Texas that does not natively use TxTag, as TxDOT does on its Austin-area toll facilities. One example is the Katy Freeway managed lanes, which were originally conceived as a self-contained HCTRA facility (the Katy Tollway) with its own pentagon shield like the other HCTRA toll roads, but which was changed during construction to use the Lone Star flag version of the double-hung toll shield. Like other HCTRA facilities, however, the Katy Freeway managed lanes natively use EZ Tag, not TxTag.
Given that shields don't necessarily line up with transponder type, I think it is really quite irresponsible of OTA to stick to piecemeal interoperability. This is why I recommend dumping the PikePass if the main motivation for having it is trips to Texas.
Edited to add: If PikePass is retained, I'd suggest checking the toll signing chapter in the TxMUTCD to see what guarantees, if any, are offered that toll payment signing will be specified in advance of entrance to the facility and that this signing will specify the transponder platform that the facility natively uses. I recall that such signing is shown in the layouts, but I have not checked that
all layouts show it, or that the text requires that motorists
always be given this information. I still think it is better to get a transponder that offers 100% interoperability rather than to bet all on seeing all of the relevant signs (message loading and truck obscuration can be a problem) and being able to challenge a toll violation on the basis of inadequate signing.