If your agent won't make the offer you want, get a new agent; it is your money not his. Hell, you even did the resurch and have a reason.
The whole point of listing a property is to look at offers; a lot of sellers will list way over market in hopes to find a sucker, how do you think the market got so over blown the last few years?
Now that the market is reversing in terms of perceived supply and demand, low ball offers will become normal.
Don’t worry about crybaby listing agents, Real Estate is hard ball, these agent’s aren’t going to be helping you make thoughts mortgage payments in the future so who cares what they think.
If they turn your offer down just move on to anther property, don’t take it personally, be business like and polite regardless of the other peoples demeanor. If they don’t want your money, I bet someone else will.
If your worried about the time needed to write up an offer, most RE forms are pretty quick but you can also have the agent write up a quick LOI, letter of intent. Basically it just states what you want to pay and any reasons on why they should accept your offer, in your case you can talk about the comps and the market.
This way you can gage the sellers reaction with out obligating anybody to fruitless negotiations, they can just turn it down if they think it’s way too low or tell you it might be do able and to submit a real offer.