I'd tried a lot of different tips with my MKII but the treble was always splashy and sibilant. I don't know how the MH1 tips do it, i didn't expect such a huge difference since the hybrids didn't do anything for the GR07 and they look so similar to these. I might order some phonak tips to check them out as well.
The only issue i have now is that i've gotten used to smoother sounding iems like the Tenore and the KC06, so the GR07 sounds a little grainy by comparison. Still, it's a good choice for when i want to hear something with a lot of texture and dynamics.