Hi, There no doubt that both types work, however the main and first question in my mind is how long do you intend to stay in your house, as everything appears to me to stem from that, as all of the systems have a relatively long term pay back/gain.
If I had no intention of moving from this house for at least 10 to 20 years I would have no hesitation in having one or the other types of solar panels fitted,
The question would only be what type and can I afford to buy myself, if I couldn't afford to buy it myself I would still have it installed under the free installation system,
Obviously everything being equal and your luck being fair and you negotiated a good deal you would make more out of it if you purchased yourself, as clearly they are making money out of the Free fitted units over and above your free electric. .
Hope that helps