Hey Rick!,
I've yet to use the TQ in place of the HI mountain cure, but this is what I came up with when researching. I had thought of doing just what you asked about , but haven't yet....
Tender Quick is a blend of salt, sugar, sodium nitrate, sodium nitrite, and propylene glycol. The amount of sodium nitrate and sodium nitrite are 0.5%.
When I looked at the Hi Mountain box for the cure ingredients it said salt,sugar,sodium nitrite(.85%), and caramel color.
What I have found is that when cure is used too long it washes out the flavor of the rub/spices that you are using. So if you try and are having a problem with washed out flavor or "hammy" taste. I would then cut back on your brine time.
I guess you realize Cabela's in KC have the HI Mountain kits?