My best friend and I just finished this on Pro, and for what we went through, he proudly said that he doesn't want to look at RE5 for a good while. It took us nearly 3 hours to get through, due to dying dozens upon dozens and dozens of times. We were a bit thankful it didn't tell us in the end how many times lol. It's probably the hardest thing I've ever done on professional, period, and will never EVER do again. Least of all by myself. Eff that.
Conserving ammo is your best strategy, like always. If you're doing co-op, NEVER venture more than a few steps from your partner, unless of course you have to do the assist jumps for Jill, but cover her whenever possible. The way the game likes to pull its typical RE BS, some hits from a majini will take most of your health, and others will even take ALL your health AND rob you of your dying state. In other words, automatic kill, which is the stupidest thing ever. That alone was responsible for at least a dozen of our deaths.
My friend and I basically just ran most of the way through, only shooting what was keeping us from pressing forward. Not at all ashamed to say that most of the time we were running with next to no health, resuscitating eachother whenever needed lol.
The finale of the DLC probably shaved 5 years off my life, because it had to be the most stressful and aggravating stand-off/gauntlet ever. We quickly strategized by backing into the corner behind the small building in the far left corner, near where Doug lands and with a clear view of the elevator and where the rocket launcher dude likes to be. We basically just each took a side and stood back-to-back gunning down the normal majini, scrambling for any ammo that was near (including inside the small building, has quite a bit). We never ventured from that corner due to the assault rifle guys on the roofs which could take us down singlehandedly with basically 1-2 bullets. We co-op'd on taking down the 2 executioners, my friend with the sniper and me with the magnum. Same with the Reapers (which killed us a good number of times; my friend said he's gonna have nightmares of 'em). We used the electric conduits to our advantage too. There were times we got down to the last 30-40 secs, and we wanted to quit sooooooooo bad. I was like, "No, we've come this far. We're not all our effort go down the drain." The time we finally did it, we were literally dodging EVERYTHING the last 10 seconds. We had absolutely no chance to take out the agitator and his buddies. I'll take care of that achievement on an easier difficulty.
But yeah, we were over the moon when we beat it. And rightfully so. I don't think I've ever heard my friend say "F*** you, Capcom" so many times before.
I'd take Chris Redfield's campaign in RE6 on Pro over this shiz.