Experience:
I am a fan of lease options. They can work. Maybe you or I would not put a permission to sublet clause in our leases but some people really do! While others reserved the opportunity to qualify a sub-let tenant, another did not.
The situation with which I got the deal was atypical but not completely uncommon.
I happened on a man who bought several properties in a short time and was overwhelmed. He had a vacant condo unit that was empty for 3 months.
He was so happy to rent it to a decent tenant that when I asked politely, he let me alter the lease.
Here is the actual sublet clause from my lease:
7. Assignment and Subletting. Tenant is authorized to assign lease or sublet the premises at tenant’s discretion.
By being able to assign the lease I didn’t need to re-lease. I could just SELL this lease , keep the money and walk away. But I didn’t do that.
I even stuck in a clause that he would pay my title insurance at closing when I bought the unit. Thank you to Carleton Sheets for that one. That saved me a few bucks. No one really knows what it means until it’s deducted from the seller’s side at closing. Then everyone goes scrambling for a copy of the lease. 
24. Evidence Of Title: Lessor shall provide evidence of Title in the form of a policy of title insurance at Lessor’s expense.
I know many lease options require the tenant to pay for repairs since he/she ultimately will own the place. Not the case here. To my good fortune the heating system let go 3 months into the lease. Seller paid.
End result:
I rented for 550/month
Re Rented for 670/month
I Purchased after 5 months at 41,500
I Sold after 3 months at 55,000
That was my ideal lease option experience.
Hope this helps
Good luck,
Jeff
P.S. 8-15k for an option seems kind of high,even for a pricier property.
Another option is getting 5 k and getting additional $$ by applying a portion of an elevated rent towards the down payment. (non refundable of course)
Also, people understand the term down payment better than option fee.