I'm a new user of Maschine, and so far - I love it. I've been reading about the upcoming 1.1 update, and I've read what a lot of users have posted.
My suggestions are as follows:
Rewire support. Machine would make a brilliant rewire host/slave! It would be a much better solution than running it as a plugin, as it would allow multiple channels of audio, transport control, the ability to run with a lot of different applications, etc. Plus sequencing through rewire is well supported in most DAWs.
Sample start-point modulation. In the old MPCs, you could use this to cut some of the attack off the beginning of the sample to simulate a softer hit. Personally, I'd like to use it for crazy wavetable-like modulation through long evolving samples. It would be fantastic if it was a real time parameter that could be mapped to a knob, and sequenced. Combined with the envelope parameters, this allows for some very interesting timbral modulation.
Filter changes. I'd like to see a resonant multimode filter included as a part of the voice architecture, and not as an effect. The biggest issue is the triggering of the filter should happen with the note on event, and not as an envelope follower. Also, I'd like a real ADSR for the filter, and while we're at it - an LFO wouldn't hurt.
One last feature I thought of that would be useful in live performances would be to do a "mixer page" where you can set levels of all 8 groups from one screen. Just toggle to it, and each of the knobs controls the level of one of the groups, maybe switchable to pan or sends as well. This would make adjusting levels of different parts very easy.