Chris_W

Try not to simply agree with the one post that gives the exact opinion that you wanted to hear. As I said in my previous post, people have been known to make a road RD work with a cassette that has a 32-tooth cog, but for this to be the case, you have to be lucky with your dropout / hanger geometry. On most bikes it won't work. Even if it does happen to work on your bike, setting the B-screw to make an Ultegra work with a 32-cog gear means that the upper pulley will be far away from the cogs when in the smaller cogs, which will make shifting in those gears more sluggish. MTB rear derailleurs actually have a slightly sharper angle of sweep, to allow the upper pulley to stay closer to the smaller cogs and still swing low enough to clear the biggest ones. Therefore, even if the Ultegra does work for you (which is unlikely) it will still never shift an 11-32 cassette as well as a MTB derailleur will.

I totally agree, for those climbs of 7% or 8% average gradient for multiple miles, you will need some lower gearing than a 34/27. The 11-32 cassette is a decent way to achieve this, but will probably require you to change your rear derailleur and rear shifter (although there are about to be several reasonably-priced 10-speed 11-32 cassettes available soon from Shimano and SRAM, you may not have enough time to wait for these). Another option would be to go with a "super compact" crankset instead of a compact. Take a triple crankset and replace the two outer rings with one ring in between these sizes (44 or 46 teeth), you'll then have a 30/46 crankset, and so a 30/27 lowest gear. You'll also need to move your front derailleur down and shorten your chain by a couple of links, but you can keep your current cassette, rear derailleur, and shifters. This also has the advantage of keeping your cassette cogs nice and closely spaced, avoiding the big jumps in the 11-32 9-speed cassette.