I use a 7wt exocett with an older sage wide arbor 5-6wt reel. Capacity is the only issue and I get around that by using braid for backing. Makes for a light fun outfit and I've taken enough long running fish with it (bonefish 8-9lb class, bonito, small albies, 20ish lb striped bass) to be confident using it in situations where I'd previously wanted an 8wt.
I like the rod with a 7wt SA bonefish line (a true to weight line) but I've also fished it with a RIO flats pro 7wt line (which is actually an 8wt weighing 210g at 30' and 250g full head) and it does well. I've also used it with an Airflo 7wt striper coldwater intermediate line and it carries that long head, which I think weighs 270g, just fine. I'd would, however, check what your RIO line weighs. RIO seems to under-rate many of their lines and I'd not be surprised if you find your 8wt line is actually a 9wt.