This may be a tad off the topic of "to agent or not to agent," but as a lawyer myself, I can tell you that very few lawyers have a clue about the publishing world or its quirks and pitfalls. Nothing against your father, who may be the most excellent attorney in the country IN HIS FIELD, if he's not a literary attorney, the most he can do, without undertaking huge amounts of research, is tell you what the contract says, but not whether it's even remotely comparable to the average equitable publishing contract.
Most lawyers have never even heard of such things as "joint accounting" in the publishing context; and they don't know that advances, when broken into increments, should be negotiated (if possible) to avoid the last payment "on publication;" or know the wording that would narrow a second book option, or .... too many quirks of the industry to mention here. Things that would have most contract attorneys shaking their heads in disbelief and trying to have stricken from the contract are common and non-negotiable for at least some major players in the publishing industry.
Anyway, don't discount the usefulness of an agent based on your access to an attorney, unless he's a literary attorney.
JD, not giving legal advice here, of course, just general information