You're asking for unbiased, so here it goes.
In Manhattan, co-broking is common. A buyer's broker's commission is built in the asking price, especially in new developments.
Personally, if I were in your shoes, I would hire a buyer's broker and sign the commission agreement. As an attorney you know without the signed agreement, your broker is just a sub-agent for the seller. If you want someone in your corner w/ comps, notices of new listings, negotiation, etc... then get one.
Sounds like you you're in a better position than most buyers, so you may not need one, but then again... look at your current situation.
Just keep in mind, if you choose to proceed w/o one, that you can't assume there's a savings, on your part. The listing agent is very likely to receiving all of the commission, which can be 5, 6 or 7%. Listing agents tend to love unrepresented buyers for this reason.
The only downside to withdrawing your offer is possibly missing out on a great apartment that you liked enough to make an offer on. Only you can determine what's more important to you: this apartment you feel you may be overpaying or getting a good value on a better or worse apartment.