Speaking for myself, I definitely wouldn't refuse to play the fifth installment. Nor would I refuse the third, although I rarely think about it, except when nostalgia becomes overwhelming. As far as I understand, the sixth installment differs from the third and fifth much more than I thought. For me, this means that it is practically a different game, and if it turns out to be good, I won't switch to anything else. I will simply play both the fifth and the sixth. If it doesn't turn out well, I will simply stick with the fifth and won't lose anything.