LogFAQs > #971007630

It seems like it, from what I'm hearing you don't actually gain less experience promoted, it's all based on your internal level (ie Vander's low experience gain isn't because he's promoted, it's because the game considers him to be level 15) so you just get free stats for no loss. Apparently Second Seals are buyable early enough that you shouldn't run into much issue with capping and not going anywhere, not to mention leveling up feels pretty slow in this game anyway.