I don't like the instant race for high lvl and instant low-lvl-people hunting, so seasons would be a good solution, but I don't see the char transfer working - especially if the server has higher rates (of course you could downscale, but more problems, and we like easy solutions).
Some other servers have seasons, where chars just get deleted, and if you want to participate in a season where you power-lvl at the start, then do some guild wars, you wouldn't have any problem with your char deleted for the next season - that would separate it from Main server a bit more, so you can't just join a season, power-lvl with potentially less ppl than Main, and get into Main with an advantage over others.
As of the Main servertype, I'm more of an adventurer, PvE, party-hunting type of guy, so I'd prefer PvE, but if there's no PKers PvP could be fine.
I just voiced my opinion, don't take it too seriously, I'm going to play whatever you do,
have a nice day.