Hi Bob,
You're right, 153 and 121 due later this year... but I was keen to try TXS and pacer needed a decoder.
Anyway I can confirm what Jonny said and the NEXT18 decoder does fit in the EFE pacer, no problems. The only issue I did find with the TXS decoder was that it initially was listed as a resettable device but turns out this is an issue with the android app. Forcing stop on the app and restarting it then resulted in the decoder being discoverable.
I'm using a HST profile at the moment :o) LOL... actually I'm quite impressed... initial app issues aside it works with my Bachmann controller as well as over Bluetooth using the app (track powered using the Bachmann basic DCC controller). Sound is a bit 'light' but I was under no illusion that the EFE pacer out of the box didn't have a great speaker. All in all for £60 compared to £100 I'm pleased... in the future I may try and improve the speaker bass response but I don't like modifying loco's I've paid full price for.
The fact I can change the sound profiles is another bonus as I can move the chip to other loco's and reblow it myself.