The HD Enabling Fee has nothing to do with the lease/own status. It is correct that you do not pay a separate Additional Access Fee (for owners), nor the lease fee (for those who lease) for the 1st box. In other words, after the 1st box, EVERYONE pays the same dollar amount for each additional box--HD boxes $1 more. Again, it is called the Additional Access Fee if you own, but titled Receiver Lease Fee if you lease. Dish has you covered either way. No one can escape this fee. Both the same but given different names. There is no advantage to leasing or owning regarding this fee.
HD Enabling Fee is only if you don't subscribe to HD services and has nothing to do with any other fees. So to repeat what others have said, for $3 more per month, you can get access to whatever HD Channels that HD tier and your equipment can receive receive. Of course, to get access to all channels that are due to you under whatever level of HD, you may need to be looking at 129 or 61.5