In most cases, acuity won't get much worse if you don't eliminate the pucker. However, increased distortion and loss of stereoacuity are likely to occur over time. Your acuity after cataract surgery might not be that great with the pucker.
If you do opt for surgery, your choice of surgeon is extremely important. You'd want a retinal specialist who is very experienced with this procedure. It would probably be a good idea to get a second opinion before making a decision.
Listen closely to what JodieJ says since he has been through this personally. I deal with this situation all the time with at least one or two epiretinal membrane patients who have cataract surgery every week. I have a retianl specialist across the street who I work extremely well with and trust completely. I always have the patients see him first and come up with a plan. If the cataract is terrible we usually remove it first and consider membrane peel with him if needed. If epiretinal membrane quite extensive and cataract quite thick, we usually have him do the membrane peel first then catraract surgery by me several months later. That's how we do it. I'm not really crazy about guys doing both by themselves on the same day. I think it is more appropriate, in my opinion to do them separately. For the run of the mill, average, epiretinal membrane case with a mature cataract, I usually do the cataract surgery first. and inject subtenons kenalog, use plenty of non-steroidal drops and prednisolone drops, and hope that the vision remains stable. They will get cystoid macular edema very easily if you don't stay very diligent with anti-inflammatories postoperatively.
MJK MD