If both charges are at the misdemeanor level, DV is the more serious class A misdemeanor in MI. Generally they don't offer the diversion if you have any prior convictions whatsoever, but who knows in a case where two charges pop up at the same time. Though, same rules apply with the drug diversion program, and I was able to get the MI 7411 diversion when I also had a concomitant misdemeanor malicious telephone use conviction, and no prior record. They ended up sentencing me to 23 days time-served in jail for the misdemeanor and 3 years probation for the 7411. Definitely talk to a defense lawyer, but may be a good idea for the defendant in this case to camp out in jail instead of bonding out, to see if they'll just give him time served in exchange for pleading guilty to the lesser offense.
If they sentence the deferral for the domestic violence, typically looking at 2 years of supervised probation, 52 weeks of DV courses, and a restraining order. Upon successful completion of probation, they'll dismiss the charge, and seal the case from public record. If defendant wants to take the DV to trial and loses, I've heard an average jail sentence of 90 days, and I've seen up to 1 year for aggravating circumstances, for first offenses.
A word of warning, the DV courses are the worst part of the punishment, and in hindsight for the sake of my own dignity I'd rather take the guilty plea. The courses are really biased and one sided, and operate on the patriarchal assumption that the man is always the aggressor no matter what. As a condition of the program, the defendant is forced to admit responsibility for the DV, which may not be the truth at all because he only took the diversion to avoid conviction or expensive trial, but he still had to enter a guilty plea. Anyways, a lot of men, many of them victims of DV themselves, walk away from this program angrier than they were when then entered, and it costs a lot of money. And, there are certain types of abusers this program will never fix (eg. narcissists and psychopaths). I did my own intensive research on DV after the course, and I learned actual truth.

