O2 sensor lag is a neat subject in closed loop tuning, but it's usually pretty consistent and can be corrected in the software (especially in systems that have short/long term algorithms). Also, lag time is reduced with higher rpm.... this isn't exactly sensor lag, but rather the amount of time it takes a combustion event to actually reach a sensor.
Almost all of these systems are using Bosch sensors, the newest being the 4.2 & 4.9 LSU. Using an Innovative controller I rarely see lag > .2 seconds at even the lowest RPMS, and usually < .1 above about 8K. If you're seeing .8 or greater combined lag numbers, there is something not right. I'm only sampling at ~18hz (bluetooth speed max) and my 'lag' never get that bad. If you could sample at 500hz (about as fast as a 4.2 or 4.9 sensor can sample), you can actually distinguish individual cylinder pulses in a merge collector with one sensor.... it's crazy. Add a little offset based on RPM and there is no 'lag' issue.
As far as closed loop systems for your bike go, they are all pretty neat, but experience has shown me that they can be... tricky to live with in the long term. All of these add on, no short term/long term, warning-less systems will usually work great for a while.... but once problems start to show up in the bike (fuel pumps wearing out, bad gas, dirty injectors, ignition issues) the system will mask it until it gets to a catastrophic level.... usually leaving you stranded and/or bashing your head on a wall trying to figure out a complex issue. 02 sensors can also fail in the same manner that fuel pumps will.... gradually over time. Without redundant sensors and visual failure indicators it will eventually catch you with your pants down. This can be mitigated with particular attention to maintenance and regular checks and service, but I'd say less than 5% of the population is either willing or capable there.
If you do want to run a system like that, regardless of who makes it, it's my advice that you set it up to get the tune happy, then remove it until you have the need to re-tune in the future. A decrease in performance is a great indicator that you have some unscheduled maintenance to do, and a primitive closed-loop system will hide that from you until it is inconvenient or too late. Just my honest opinion.