If you have a relatively new machine and Firewire or PCIE, the latency is truly negligible. Pitch->MIDI tracking can be usable but I just don't trust it enough and honestly, being creative with audio effects and routing is just way more engaging. I can run some pretty serious effects schemes in 3ms or less with the RME Multiface II without pushing my CPU half way.
This is way more than I'd ever realistically use and I'm still not at 50%. I have here:
-Opto compressor
-Multiband distortion used as a hard gate
-3 oscillators, 2 routed to one bus and the other dropped an octave below sent to another
-Up to 8 filters, 12-48dB, roughly 10-12 potential different models for each filter
-Graphical waveshaper for higher oscillators
-A digital EQ low-passing the subs I don't need for the lows
-Pulteq analog modelled EQ for character (relatively resource intensive)
-Light chorus on the highs
-2 different rhythmic glitch / sequencing plugins that I can bypass and send various program change messages to with a foot controller
-Hardcore squashing limiter on the master out
The one thing that I do miss is overdriving my MF-101, but I'm demoing SoundToys native right now and FilterFreak is blowing my mind and freakishly close. It's a very expensive bundle but I can get a discount and the filter, phaser, delay, and decapitator are all the finest in their class that I've tried by pretty astonishing degree.
With a solid state drive in your laptop, that whole mess will load up on a program change just peachy.
This is another super fun plugin: The Korg MS-20 filter section courtesy Korg themselves. I do not miss my Robot Factory at all.