Well lets look at it here:
Out the Door: $28,000.00
Add-ons: $4,400.00
Total "Invested": $32,400.00
Insurance Offer: $26,600.00
Difference: $5,800.00
I guess I would attack this from the following perspective, Call a couple of dealers. Choose 3 lets say and make them, your local dealer you have a relationship with, a national dealer you trust, and a completely unknown and perhaps hungry dealer that someone you know has had good experiences with.
I would call all 3, tell them you are looking for a 2011 / 2012 with the following options (XM, GPS, Elkas, and a Corbin Seat) and let them price that out for you. Now obviously we have not introduced depreciation into this mathmatical hodgepodge I have thrown out here, but it is kind of a starting place. (Usually brand new items take a 10% to 20% from Brand new to you drove it 1 mile ~ [$28,000.00 * .2 = $5,600.00] Dropping the value to $22,400.00 by the time you get home) take this number add your 4,400 (Total $26,800.00) from earlier and $26,600.00 is just 200 off.
Then hit ebay / craigslist / the WTS here (I think we had a 2010 RT booking at $17,000.00 from a lady recently). If the dealers arent far off the mark, and you could find a replacement for around 17,000 to 18,000 heck you could roll at an $8,600.00 profit which is lots of sparkles.
While the bike was a total loss, is the radio, gps, shocks or Seat Recoverable in your opinion? and if so do you have a chance to take them? I would hazard a guess it wouldn't change the insurances point of view.
Anyhow, just throwing out some math, figures and ideas for you sir. I am glad you are getting better, and that a spyder might be in your future, I hope it all turns out very well!