Re: What do you think? Shift kit or new sprocket?
Oh yes, one word of advise, if you so choose to take it.
Get the "Deluxe" shift kit because it comes with all the tools and a few nice options.
If you bought all the extra bits individually, it works out more expensive, also, buy the optional dished 30 tooth chainwheel sprocket (or the 24 tooth chainwheel sprocket if you are towing a heavy trailer) and get the 9 tooth jackshaft sprocket.
This combination gives you an effective low range chainwheel gear combined with a high range chainwheel gear - if there is enough space to keep your front derailleur, you'll be able to shift chainwheel gears on the move, otherwise it's a manual process, but it's not a big deal.
The hill climbing power is just amazing with a 9T jackshaft sprocket and the 30T chainwheel sprocket and a 34 or 36 tooth 1st gear on the rear wheel cassette.
With the optional 24T chainwheel, you'll be able to climb vertical inclines towing 50 kilos (110 lbs) behind you.
At the end of the day, it's not about going down the road at ridiculous speeds, but more about getting up and over hills, regardless of how steep they may be, without straining your guts out - let the engine do the work.