i would 100% recommend it, went vet on my trial account that had pretty much every vanity item / achievement obtainable - bloodthirsty, master of wsg/ab/eots, both justicar and conqueror, etc.
makes it a lot more convenient for grouping and contacting bnet friends (via the game client), and pvp is much more enjoyable with enchants - especially if you're playing underpowered specs that greatly benefit from them, e.g. affliction warlock. the ability to join guilds is also nice as it nullifies the need to use f2paddon (assuming that said trials are now your guildmates instead).
also opens up additional opportunities for achievements if you're still looking to obtain more - would have to switch over to character specific though.
a downside is that vet can be overwhelming if you have f2p alts spread across many servers, as you'll have to farm the gold needed for the bis boes & enchants. xfering the boes individually can be expensive so i would prioritize just gearing the characters that you're looking to play most - this isn't an issue if all of your characters are on the same server, or one with a high twink population, as you'll have easier access to bis gear.
if you're someone who cares about f2p "purity" then you might not want to upgrade, yet i've always found the concept ridiculous when p2p assistance is required for most of the difficult achievements.
gl on the decision, i was initially hesitant but i have no regrets - adapted to the current state of the bracket by going vet and it has paid off for me.
