Why would I find being given the "benefit" of arriving a day early to be a perk that compensates for flying in coach? Why would I want to be away from my family for one extra day? No thanks.
When I travel, it is to close deals worth at least 9 figures. The cost of the J ticket is insignificant compared to the value of the deal. I arrive the day before the meeting at the earliest and often go from the airport to the meeting with a short stop at the hotel (or arrival lounge) in between. Why? Because I usually have another meeting or other work obligation the day before the meeting.
Also, if you work for a company that can negotiate substantial corporate discounts, the cost of the J ticket is not going to be that much more than the cost of a Y ticket, especially in light of the value of the deals we are doing.
I would absolutely not use my personal miles to upgrade business travel. Those are our miles that the family earned by being away from my family and are for our use (yes, the family staying home endures hardships when one person is traveling for work).