When I 'returned' to sea fishing two years ago I also wanted to use the Shimano (as it seemed to be top of every 'poll' I read) However I went to a tackle shop and although he stocked the Shimano and would have sold me it, he recommended a Daiwa Regal. He used the arguement that you've already mentioned regarding corrosion and sand wear. It made sense to me particularly as the Daiwa, being less engineered was more robust, as well as being half the price! I've always used 'fresh-water' reels in the past and made them last by assiduously cleaning them after use. My Abus get the same treatment anyway! However I have to say that my Regal's still going strong and I've recently bought the smaller (slightly) 4000BRi, which is not salt proofed, for another rod. Both have 'Twist-buster' (great name!! but seems to work) mechanism/system to avoid twisting line under pressure. Doubtless the Shimano with care would be 'better' but probably not TWICE as good! I use my Daiwas for spinning and light ledgering when the Bait-running system allows really good bite indication.
As an experiment I recently bought a brand new RonThompson beachcaster for £10 and a larger baitrunner for £15. (name escapes me - but not a front runner (pardon the pun!) which will get the TLC it obviously MUST have to last. Must be said that non of my fishing tackle, including rods, ever gets the bully treatment. Having witnessed some anglers using their stuff for 'winching' I can well understand that some cheap stuff gives up the ghost.
My advice would be not to try manhandling rigs and leads through kelp with your Baitrunner! I'm sure you have more sense than to try it but there's nothing says you can't put your rod down if you get snagged and pull the line out by hand! I carry an 18" piece of broom handle to help with this process, seems easier to wrap a few turns around than bedding line down into the coils on the spool or stressing the cogs, bearings above their designed limits. If you fish a pier, then buy yourself a dropnet!!!!!! Good luck with your tremendous reel!!