Originally Posted by
HillRider
The lack of chain wrap capacity isn't a deal braker. Exceeding the wrap capacity only means you must avoid using the small chainring with the smallest cog or two combinations or the chain can go slack. This is just an inconvenience, not the potentially damaging problem not being able to shift to big-big can be.
+1, It's fine to overcapacity an RD if you can accept not being able to ride the granny with the smallest few cassette sprockets, In your case those with less than 4 teeth larger than the smallest, though you might do a bit better than that. Whatever you do, don't fudge on the big/big side. Accidentally shifting into a combination for which your chain is too short is the kiss of death for your RD, rear axle, and/or derailleur hanger.
Since you were near capacity with your old setup there's a good chance that the 2 extra teeth on the cassette might be a deal breaker (measure big/big + 1inch). If not, consider replacing the chain with a new one, and keeping the original to rotate back into service at 1,000 miles or so. This will improve the cassette life, and rotating two chains will continue to yield benefits.
Lastly, looking at your needs, you might consider replacing the granny with a smaller one, say 28t or 26t. This will give you more bang in terms of lower end gearing, cost less than a new cassette, and not require scrapping a chain because it's 1" too short.