I'm a satisfied owner of an 89RB, prety similar to the 86 just a different plan, in fact it looks like the 89RB is pretty much the same plan as the 80rb. I also have the 4G HWT, for what it's worth the claim it is a 'quick recovery' model. All 3 of us can have a 'navy' shower without running out of hot water.
I'm not a fan of those horizontal tanks, they are expensive to replace. I personally could never get buy with those small tank sizes. I sure like the windows on both sides of the overhead, that's the one thing I don't like about mine.