Harrah's properties often have designated days where you can trade Reward Credits for Cash at half face value. So, at a minimum, 1 comp dollar is worth $0.50 cash.
Normal Harrah's earning rate at video poker is 1 Reward Credit ($0.01 in comps) per $10 coin-in. Earning 7X gets you 7 cents per $10, which is 0.7 %. Half that is 0.35%.
The vpFree page about Showboat AC shows they have 9/6 Jacks in many
denominations.
(Dead link: http://members.cox.net/vp_free/E_SHOW.htm)
With 7X RCs valued at half-price, that's a slight loser:
99.54 + 0.35 = 99.89% return.
I bet that heavy play on this game would generate coupon offers worth much more than the 0.11% expected theoretical loss.
In addition, there might be 9/6 games there that award Bonus RCs in addition to Base RCs, which would trim the edge some more.