Everyone who wants Ference on LTIR for cap purposes should read this article.
I have posted this before but will repeat it here:
It is wrong to believe that a player on LTIR generates no cap hit from LTIR. That is one of the big misconceptions. The full cap hit counts and while there is relief this can have consequences. For example, for a team like the Oilers with a lot of bonuses built into their contracts having players on LTIR can be problematic. You don't get cap relief from bonuses from LTIR so if you have to pay out the bonuses that contract you put on LTIR could trigger a significant carryover that could easily be more than Ference's buyout.
And I will illustrate one other consequence that could actually play out for the Oilers if they are in playoff contention next year.
Suppose that the cap is $73M and that with Ference the Oilers were right at the cap next year to start the season. They put him on LTIR and now can add up to $3.25M. And suppose that they add Reinhart to replace him at $.863M. The Oilers are technically over the cap but they are compliant because of the LTIR. If they play that way until the trade deadline at that time they could add a player whose cap hit is up to $3.25-.863M= $2.387M because of the relief they get from Ference's LTIR.
Now lets assume that instead they buy him out and again start with Reinhart in place. The buyout costs them $1.08M and Reinhart cost them $.863M leaving them with roughly $1.3M in actual cap space. But at the deadline they would still have $1.3M to spend with only a fraction of the year left. In fact, this way they could add a player with a cap hit of roughly $6.2M and still be compliant. So by using the buyout you have effectively gained $4M in cap space at the deadline next year when a team like the Oliers could make a play for a big contract UFA.
If they are not right at the cap to start the year then the benefit with respect to both the overage penalties and space at the deadline is even larger than the scenario above.