These changes seem great.  Good job mods and whoever else came up up with them!

sebi wrote:

The message you submit will be sent to us, the target user or anyone else will not see it.

It might just be because it's past midnight, but I completely failed to properly parse this sentence the first time through and had to reread to the post to figure who would be notified when a user was reported.  I think a comma is too weak here.  A clearer rewrite could be

The message you submit will be sent to us; neither the target user nor anyone else will see it.

I hope I'm not coming across as pedantic!  I just think it would be nice to make clear that users will not know who is reporting them or that they have been reported so people can report others without fear of reprisal (unless they're abusing the system).

I'd heard about the DoctorGraim case, though hadn't looked into the full extent of his duplicity.  While it is unfortunate this has happened, I trust it is a rare occurrence.  And, as HikingStick mentioned, no amount of precautions will stop a dedicated scammer.  I understand wanting to protect new users, but trade limitations will hinder a significant portion of users in order to make a handful theoretically less vulnerable.  I feel a New User Orientation would be more effective.  Teach users what to look out for instead of hamstringing them right out the gate.  It wouldn't be "There are sometimes scammers here!" but just general tips that could make their Deckbox experience more pleasant.  Things like stay cordial, feel free to turn down a trade, you can block users if they're being belligerent, give your trades an actual name, use the chatbox, watch out for dudes with a bunch of active trades, it's generally expected for new users to send first, etc.  Then have a "Check out the New User Orientation (this message will disappear once you have completed it)" alert on the trade and homepage of users who haven't done it.  Users will read through the orientation, answer a question (to get around the tendency for people to not read things and just click okay), and now they're informed.  It seems easier to implement from a coding perspective too.

@lorddax
That sounds like micro-transactions.  Mobile games say micro-transactions are a good way to make money, but I've never spent money on a time-waster game so I'll just have to take their word for it.  I can't think of things people would be willing to pay a one-time fee to unlock, but I'm also not the target demographic of micro-transactions.

Amurphcs wrote:

What if the following was used:

New traders have a maximum value cap of $400 (i.e playset of tarns or lotv, or a couple gaea's cradles), and may have no more than 3 trades open?

sebi wrote:

I mean it would not prevent you from trading, a new user would simply need to wait for his cards to get to destination before opening new trades for other cards. For national trades this would be 2-3 workdays usually, no?

Capping the number of open trades seems bad for trans-Atlantic traders.  Yes, it does only take 2-3 days for national trades, but I don't think very many people outside of the US are trading primarily with their countrymen.  Much like the proposed $50 limit, I would end up spending a lot of time just sitting on my hands waiting for my cards to reach Florida.  Capping the number of open trades also feels like it would lead to a drop in courtesy.  For example, Easter is coming up.  I'm not sure how it is in other countries, but things shut down for four days here in Germany.  It's a good excuse to travel abroad, or maybe just visit your grandma out in the country.  Currently, if a trading partner was like "Hey man, I'm going to be away for five days, is it okay if we pick our trade back up then?" I would have absolutely no problem with letting it sit.  With a 3-trades cap, I would be encouraged to cancel the trade in order to keep my slots open.  Sure, canceling a trade isn't a hostile action, but it still feels unpleasant when both parties are keen on said trade and will likely lead to fewer trades overall.

I dislike this whole idea.  Trading restrictions (value and levels), levels, how levels are advanced, all of it.

Levels: L1s can't trade with other L1s.  Wanna trade your Drana, Liberator of Malakir for 2x Cinder Glade?  Tough.  As a user with low feedback who loves janky rares, I'm mostly interested in low-value (which carry an inherently lower risk) trades.  This rule would seriously limit my ability to trade random little junks for other random little junks.

Advancing: Having advancement be tied to the value of cards traded seems bad.  I'm far more likely to be comfortable trading with a dude who has made a dozen $10-15 trades than one who traded away a playset of Aether Vials and a pair of shocks.  A "number of trades or $xx, whichever comes first" threshold makes far more sense.

Value Limits: This feels downright hostile to new users.  I would be disinclined to trade a Magus of the Moon to a Canadian L4 since his $30 price tag would eat up the majority of my L1 limit for a full month.  Did I get lucky and pull an Expedition at draft?  Looks like I can't trade it locally or here.  Sure, I could pay money to get the restriction lifted, but that feels an awful lot like bullying.

Foreign Users: I don't live in the US.  I have no problem trading worldwide since postage is 0.90€, but all trades to North America take about a month to complete (send first, 2 weeks until receipt, 2 weeks until my cards arrive).  It took a while to cross the 5-Trade threshold, and that was without additional limits being set on my ability to trade.  While I heartily recommend Deckbox to my buddies, my recommendation would change to "It's nice for inventory management, but you really have to work to get anything out of the trading system" under the suggested changes.