We considered buying a leasehold house, but decided against it. The main reason being that we weren't convinced that there wasn't some catch. We wanted the security of knowinng that it was all ours and that we weren't going to get caught out with anything.
So if we had bought it then we would have felt that we needed to buy out the lease. However we were mortgaging ourselves up to the hilt and the additional £500 seemed like a huge amount of money to us at the time.
We told the sellers that we would consider it if they bought out the lease, but they were reluctant to do that as 'it would only cost us £500' so they thought we should do it. If it was that cheap then why weren't they prepared to do it.
It just didn't sit comfortably with us at all.
So i would suggest that although she is happy with the agreement now, she might want to consider it at a later date if she wants to make the house easier to sell