FWIW, I've had very little difficulty get even e500s to clear. CR-1s usually clear at booking (or I try a different routing).

I used to often let e500s expire for the miles (I had plenty of CR-1s), but recently used a bunch (before one member of the secret society got UA to reverse its policy) without any problems.

Of course, I typically use e500s on widebodies and 752s. On 319s and 320s, it can be difficult.