I use Expert Sleepers with various sequencers, all synced to Logic Pro.
The Silent Way software converts MIDI data to audio signals, out through an ADAT port into am Expert Sleepers module, which then converts the audio signal to CV. Since its an audio signal, not really MIDI, it is as fast as light, virtually instantaneous.
Silent way can send gates, triggers, pitch cv, envelopes, LFOs, pretty much anything. It can also send a sync signal. I can lock various sequencers to a given tempo, and if they allow, can also start/stop/reset them by pressing space bar.
With this configuration, I can sequence hardware with virtual instruments without latency. I use mostly hardware synths, the modular a lot, and do my drums ITB. Everything is locked in, it just works. The piano roll is still the king of the sequencers, at least for me, as it can be any length, send velocity, record my playing, quantize a lot or a little, randomize all kinds of stuff. This allows me to get the benefits of both sequencers at the same time.
Layering in hardware is a lot harder, which is why you don't hear it a ton, but I certainly do multitrack, although usually the same sound, slight detune, and panned. With the modular, I can send the same signal to different voices, and then record them on their own channel.
Expert Sleepers also now makes a MIDI port module, allowing you to sync all computer DAW, CV, and MIDI. It sounds crazy, but it really works. I will NEVER not use it again. I can sequence poly synths through my modular....thats crazy. How about sequence a software synth with a hardware CV sequencer like Intellijel Metropolis? And have it in sync? Yup, it can do that too.