I'm a recent convert from NI Guitar Rig. The amps in the 11R steamroller the GR5 amps, and the GR5 VST sorely lacks a Unvibe. But there are a few features I really miss that could be easily addressed in an update:
1. Global, assignable LFOs, step/analog sequencers, and input-based envelope generators. With this last one, we could make our own Autowah. The 11R is top notch for classic sounds, but less so for sculpting modern ones.
2. Pitch shifter. The NI VST is famously bad at tracking, having one is a must.
3. Multiple cabinet mic'ing and parallel rigs. True, there might not be enough DSP resources, but if so it's pretty cool to have.
4. As mentioned before: Autowah.