So here's my take on this, as another 'generally solo' player.
1.) F8C is useless, no loss there at all IMO. If you want a solo a heavy fighter, I think the MX, Vanguards, and even SuperHornet are all better options, both now AND going forward.
2.) Hercs are in general about the biggest ships you can solo effectively, and I expect it'll stay that way too. Now, A2 is awesome if you like/use the bombs, but I'd venture to guess as a solo player you actually DON'T bomb stuff all that often. I also wouldn't be surprised if CIG moved removed the bombing capability from the pilot seat in the A2 before too long. Though it's unloved now, my guess is the larger cargo and heavy armor will really make the M2 shine in the long run.
3.) While Hercs are the most EFFECTIVE solo big ships, that doesn't at all mean you CAN'T solo other big ships. I solo my Carrack and Polaris All. The. Time. Is it a pain and does everything take longer? Well yeah, but especially with the PD turrets on the Polaris, it's really quite fun to park it and then fly a light fighter out of the hangar. I'm expecting similar fun to be capable, if a little clumsy, with the Perseus in the future. In fact I'm eyeing one myself, but haven't quite pulled the trigger on the chain yet.
4.) For a all-around solo ship, let me throw out the new Asgard as a contender to the Herc. No it's not as big, but it's still pretty darn capable and damn is it just a joy to USE. Just a thought!
5.) 600i IMO will ENTIRELY depend on IF/how it's touted rework pans out. As it stands now I feel it just sucks compared to a Connie, but I'm holding on to mine in the HOPE that changes but damn we've been teased about that for SO LONG now. . .
6.) Currently Perseus is $675 and A1 is $750, so you always *could* re-upgrade to an A1 if you really wanted. . .