Will the CS-6700 11-28 cassette work as...
Will the CS-6700 11-28 cassette work as replacement for CS-4600 10 speed 12-30? What do you think about chain length?. Bike is full TYiagra compact double 50/34 up front.
I would recommend that you consult your local bike shop mechanic (and you could be a nice person and buy him or her a drink in exchange for the advice). But if you are the "do it yourself" type... this would be a suitable replacement, you won't miss that 30 tooth cog. Ultimately, chain length will not be a problem, although you may have to shorten the chain slightly. Just ensure that your current chain is compatible with the CS-6700 (and isn't worn out). If it is significantly worn or stretched, get a new one.
That said, I would check the minimum capacity of your rear derailleur, verify that it can work with an 11 tooth cog (it probably can). The upper capacity won't be an issue since it currently manages 30 teeth. Hope this helps.