I'd like to add another vote in favour of this change.
We're a mid-sized guild (50+ accounts), and we hit a wall around level 80. We have a number of casual players, and we took a decision to live with not being able to make renown work for us rather than booting anyone. The fact that we couldn't make it beyond 80 was discouraging enough that many people stopped bothing with renown rewards, to the point that we were slowly back-sliding. This week, we've reversed the trend and we're slowly heading back to 80. With Mabar, I doubt we'll actually get back up there before the trial ends, but personally, I've felt energised to play again by the renown changes - feeling like we actually have a chance to get that top-tier ship makes it far more worthwhile. We have had a few people self-boot, or remove alt accounts to try to reduce the penalties.
To those who think the system needs to prevent bumhats from exploiting (e.g. invite a bunch of newbies, get to high level, boot the newbies), the problem is that making rules (that affect everyone) to control the actions of a few bad apples tends to screw everyone EXCEPT the bad apples (who simply find other ways to game the system at the expense of others). By the same logic, we should get rid of guild chests, or guild plat pooling (towards another airship), as what's to stop people inviting a bunch of newbs and getting them to contribute something as an 'entrance fee', then booting them? How many times have you heard of people joining a guild just to loot the guild chest? Ultimately, like any relationship, there has to be a level of trust inherant in a guild; if the trust is lacking, the guild will generally disintegrate anyway, or end up shunned and ignored by everyone else.
I have no problem at all with people forming Korthos army guilds to hit top guild level. If they can make it work, more power to them. I personally would never join such a guild, and we'll never take people on just to boost renown. We recruit based on whether we think someone would be a good fit for the guild, and we do reject those we think wouldn't be, or who don't make it through a trial period, and the proposed changes to renown won't change that at all. We try not to let renown decay be a factor in recruiting, but it'd be really nice to know that it definately wouldn't be (if this change becomes permanant).
Although there will be a few mass-invite guilds, I really don't see that the majority of guilds will do anything very different; many people seem to prefer being in a more tight-knit grouping of like-minded individuals, and you don't get that with a mega-guild. For those who enjoy being in a 1000-char guild, why should they be penalised? So long as I don't have to play like that (and nothing about these changes forces me to), why should I care? Guild reputation is based on the actions of members: if a particular guild is known to have a lot of people who don't listen or don't know what they're doing, they'll find people don't group with them. It's happened in the past, it'll happen again in the future, and nothing about guild renown changed that. Reputation takes a long time to build up, and almost no time to trash. The slight down-side is getting spammed with invites on non-guilded characters; maybe a way to disable guild invites (part of the lfm-invisibility setting, perhaps?) would solve this? Even if we just had to live with it, it's not a huge deal, and I know of plenty of people who formed 'free parking' or 1-man guilds to get around this, back in the day.
To those in smaller guilds, who don't see a lot of benefit in these changes, I'd like to see some more change that specifically targets you. However, the current trial doesn't seem designed to address your issues, but rather the issues of large guilds getting stuck. Take comfort in the fact that renown suckiness is finally being addressed, and instead of whining about how it's not fair that large guilds are getting all the lovin', continue to provide constructive suggestions for how things could be made better for you. For example, it seems like the renown multipliers for smaller guilds could be considerably boosted up to make the playing field a bit more level - this would (I assume) be a reasonably easy change to make, since it doesn't require changing the underlying mechanics, just some constants.
In summary, the renown changes being trialed have been super-positive for us, and I really hope to see them become permanant ASAP. Allowing massive guilds an easy ride to 100 as a side-effect really isn't a problem; they still have to trade off the intimacy of a smaller guild for the management headache of herding cats to get the benefit. Please continue to consider how to sort out other complaints, but let this be the first step to a renown system we can all enjoy.