I was in the same situation, and was torn between ASP2, IBU3 and TK60.
Only thing i can say is that i didnt like the sound of the IBU3 when used with Abrams sound, other sounds may be different.
The sound quality of the ASP2 seems to be very good, the Juno board is within the package as far as i know. It is just that the sound is not directly integrated to the board itself.
Problem with the IBU3 was that the transitions between idle and revving sound were escalating instead of a smooth transition.
The ASP2 had some similar problem but this is also only for the abrams sound which is available for the ASP2 as Leopard sounds are.
I now go with the TK60...
So between IBU3 and ASP2 i would tend to the ASP2 but keep in mind that you may need a specific radio (FrSky X9D or Taranis, etc.) because the configuration is virtually done via config file in the radio.
Dont know if a standard 4 channel radio will work with the ASP2.