Should I "betray" my realtor?

[Alessandro Cardito]

I'm looking to buy a property in Hoboken where the market is not so hot at the moment and Zillow forecasts a 5% decline in the next year.

Based on my research and financial calculations that's still the best option and I want to go on with the purchase. 

It's clearly a buyer market- the properties I'm looking at have been on the MLS for 100+ days and new comps keep coming up, I've put some offers through my agent 20% below asking, but my agent keeps saying the seller's agent is not positive about my offer and plenty of offers are comin in right now (yeah...sure...)

My agent has been good to me and advised me well in the past, but I feel someone a bit more pushy and stronger at building logic arguments would be able to persuade the sellers agent and eventually the seller, making it a win-win for them and myself.

I've told my agent a couple of time what she should say and to put pressure but I've the feeling she's not able or not willing to.

Would you think it's fair to go to another agent (which I know and has been recommended), being transparent with him and give him the challenge? If he manages to close the deal at the price I've in mind the fee it's for him to take, otherwise I'd stick with my current agent...am I being fair? How would you otherwise deal with this situation?

I feel she's not helping me making the most of a buyer's market!

Thanks for your experience!