Warmongererererer diplo penalty doesn't matter anyway, really. If someone's gonna hate on you for being a warmongerererererer then you don't need em.
Yeah, the problem there is you can't get RAs while they're spreading among the AI like VD so even with Espionage it becomes harder to keep pace with AI tech.
Current game I was dominant tech leader until Renaissance... almost everyone has the warmonger flag (except 3 China, Arabia, India but none of them want DoF so no RA either). I had two choice cities for enemy spies (my capital was highest science another coastal city was highest population - which is a flag for AI spies to tag since that assumes good science output and it was indeed 2nd in output but a far margin lower than capital) and only one spy so while I caught a few at least half the AI were getting free tech... Arabia entered Industrial half a dozen turns before me (now with second spy I'm trying to steal from him to at least equalize).
I've since lost warmonger flag with Polynesia, gained it with India and gotten a DoF back from Poly and we're doing RAs but Spain is in RAs with Inca, Maya, Arabia, India, Ethiopia and threatens to quickly surpass my tech. It's making the game a bit interesting granted, but if this trend continues I'll soon be lagging behind everyone else in tech badly...
Right now Spain is working with Maya/Ethiopia/Inca/India (despite the fact Inca is at war with both Ethiopia and Maya).
Polynesia has returned to being my friend (he asked me at attack Ethiopia with him and I said yes - Ethiopia's down to 3 cities but with that UA are putting up a nasty fight since they're close to me in tech).
Arabia is remaining neutral (no DoFs no Denouncements) but has an impressive science base and able to research well on it's own (plus it's been stealing from me) and are unlikely to join me because they're Guarded (even though I forgave their spying and the only red modifier is "Built Wonders They Coveted" even though he's boggarted the last 5 wonders... he's coveting pre-Medieval ones he noticed in my cities it appears).
China is Friendly, keeps renewing luxury trades but no DoF yet (the did have early tiffs with Polynesia but there's no "Friendship with one of her enemies" modifier. She requested me to join in war against Gandhi, I said yes since he denounced me with NO reason listed in diplo modifiers; Gandhi was simply Guarded with the only modifier being "No contested borders" until it added "Has denounced you") although I'm hoping to bring her into a block with Polynesia and myself since Spain just attacked her (while she's committed against India) and I denounced Spain in return (so did Kamehameha).
If I can manage to wipe out Ethiopia (without making everyone hate me as a warmonger again, hoping to let Polynesia, Inca or my nearby city-state ally take their last city) it might help weaken Spain's block a bit since Ethiopia was pretty much the common thread keeping Maya and Spain together (The Mayans hate the Incans and will probably stop being so friendly with Spain if she does turn on Pachacuti and I'm hoping to assist China is eliminating India from their continent).
On a side note, game has gotten REALLY fun right now (especially with the two front war) since we're all so close in tech. Had some good high seas battles with India (caravels, frigates and privateers clashing in the deep ocean) while carrying on a decent landwar vs Ethiopia (crossbows and muskets both sides, although I have a few cannons over there and he's still using trebs). And I'm having to keep an eye on Spain because she's been building up frigates, privateers and tercio... probably going to harass my CS allies Milan and Vatican City again while taunting me to do anything about it... (hope she does, I've just build Military Academies in my good producing cities and am about to replace most of my back city garrisons with higher xp units which will give me a steady stream of semi-experienced units to gift my allies for a proxy war).