Requirements could be a combination of anything really - time on site, money spent, number of orders, seller’s reviews or most useful, a combination of these with a certain ratio. ie. a buyer who has been here 2 years (positive) but made 2 purchases (negative) with a combined value of $2000 (positive) should not be a TRB. Someone who has been here a year, made weekly purchases with a combined total of $2000 and has 40 x five star reviews from sellers should be a TRB. A very loose idea but parameters could be set according to site norms in terms of the “profile” (not location but spending habits) of those who chargeback and those who are long term buyers.
The biggest issue with the whole concept is of course, the payment issue - as you say, bigger value, bigger impact. Yes, I have experienced a big job recently and all went exceptionally well (although technically, there is still 3 months til I am actually in the clear from a potentially devastating chargeback).
The thing is, I have turned down opportunities to do similar sized projects, and I will never do a $10k order (or allow a buyer to spend that kind of money with multiple orders within a short space of time) simply because of the risk involved. It is not just the risk, it is the not knowing how a chargeback with an order of this size would be handled. The big $5k chargeback reported on the forum was sorted out positively but my own $100 one was not and the buyer involved is still active here. There is no real public protocol for this situation and having looked into it quite a bit, nobody else does either. It is always hit and miss. I would love Fiverr to be Doers and be the first platform to say that they really value their sellers and will rigorously defend against unfair chargebacks.
The solution I see to this seems exceptionally simple and is probably not an original one.
A clear process, outside of normal CS, to be set up for chargebacks alone - 1 or 2 people could probably manage it, especially as PP allow 30 days for an initial response. Their job would be to internally assess whether a seller delivered through a report form of some kind that a seller fills in etc. They then agree or disagree with the seller - if they agree then they go to PP and fight it.
Paypal itself is not a difficult system to win a case on, once you have proof of delivery. I would even be happy to pay a small percentage of the money recovered if this was in place.
The premium service I envisage would be limited to certain categories such as logo design, web/app design, potentially SEO and a few others. From what I read, and the number of posts on the forum about these categories, these are the ones which are extremely problematic. If I want to find a logo designer who will draw from scratch, send me sketches/concepts initially, work in an ongoing process etc and I am willing to pay $500+ for this, I need to sift through 40,000 gigs for this. The featured and TRS of logo design generally do not offer this service off the bat and the search system is not good enough to whittle these down for me.
As for differing levels - people need to be (nicely) told to stop moaning about it. I don’t think TRS gives a big difference in sales, it doesn’t appear that way to me anyway.
Levels could do with an overhaul for sure - the gap between lev 2 seller with 50 sales and TRS is vast, a level 3 could be introduced. That said, the system being based on number of sales has been outgrown and should have been updated/upgraded when packages/bespoke pricing was introduced. A premium gig seller (or anyone for that matter) might only have 5-10 gigs sold per month but earn $5k. That would stop them ever getting up to level 2 yet the guys with 50 x $5 sales are leveled up within 2 months!