I have two practices giving varying prognosis for my teeth. Can you advise?

Q. I am male, 65 and had 2 upper jaw implants fitted in 2007 to retain a full over-denture. Both implants failed and had to be removed last year. I now have 2 proposals before me for further treatment, one from the original practice and a new, second opinion. They differ in some fundamental ways and I\’m having trouble deciding which, if any, route to pursue. Both propose bilateral sinus lifts, followed after a few months by 3 implants on each side and a fixed bridge. One proposes implant fitment followed by a week without the denture then 4 months healing time, but the other offers a temporary acrylic bridge within 24 hrs of inserting 6 Astra implants, followed a few months later by a final metal bridge. The traditional quotation is certainly cheaper, but involves two 1 week periods without any upper teeth. In view of my history, could you comment on the relative merits (especially probability of complications/failure) of the two approaches? Thanks.,