A few thoughts:
1) Increased power: I tend to like it. (make no mistake, this will be a significant increase in power for high reincarnation chars). An extra 12 ranks is huge - thats an entire full immunity, or its just enough to allow the damage shield ranks to look mildly affordable. An extra 12 to con/str/dex is great on a tank (I'll be taking max dex please thanks) An extra -6ss... wow. Add in some extra hp, moves, etc... for shits and giggles and this is a very large boost if you follow through with 6x
2) Content/replay-ability: Not sure i like this aspect - This is not really new content, but it encourages replay ability for the lvl 1-29 range. I enjoy the high rank and higher lvls zones - this obliges the extra time spent to be at the low lvls. That's not necessarily a bad thing, but i think it will be rather dull and feel grindy. Sure, i have the choice to not opt in, but who wants to give up on power so ill probably opt in and be annoyed at the duplication of low lvl zones again and again. Some PCs will burn out, some PCs love low zones and wont care. Some folks will ignore it entirely - but i suspect not many will.
3) Grouping: I think this will fragment the player bases levels. I don't think it will generate a lot of random LFG shouts. Rather, i predict 2 people simultaneously deciding to reinc and powerleveling to 30 at lightning speed ignoring the world. This may actually make it harder to group because of fragmented levels. Not a huge issue, but sort of not great. This will probably impact larger clans who are zoning more and will give solo players a lot more solo progress to work on. I'll be annoyed that when I'm not reincarnating and want to zone my clan will all be lvl 14, and vica versa. This is good and bad.
4) Exotic race rush - this removes the rush to legend/throw out char/make an exotic go to move. I like that - always seemed weird to have a rush char and then start over again.
5) Re-level penalties: re buying ranks - not a big deal. Cash comes and cash goes. This is the penalty i care about the least. Honestly - if I'm going too reincarnate at 1x i probably wont even bother buying most ranks anyway. Ranks matter on big fights, but if I'm looking to maximize exp/hour ranks aren't a gigantic benefit. When I'm leveling to legend, half the time I don't buy ranks cause I'm just saving up for legend. Or maybe everyone will just buy only +dam ranks til they are 6x?
6) Re-level penalties: skilling again - at first this sounds really shitty. Skilling is one of the worst parts of the game. I guess this is offset by the fact that i don't need to skill unless i'm going to legend and there is no sense legending if i am going to reincarnate. So I believe I would just skill up 1 weapon skill and ignore most everything else like field medic or battle cry until my 6th reinc. In fact, for my first 5x i i would ignore most skills completely and just learn passively what ever i'm using. That seems sorta weird, but i guess it makes the resetting of skills sort of moot. Side note: Will i have a faster time skilling up on my 6th reinc on field medic if i left my field medic at awful 5x?
7) Re-level penalties: exp is slower. That sucks. I get why you want things to be progressively more expensive, but that just means increase the low lvl grind. And the low lvl is pretty much is a grind. Very few people explore at lvl 12 - almost every levels as fast as they can. we call it a rush - we are all rushing! Sure, i could stop and try to enjoy the scenery more - but I'm just not that sorta player.
Do we think anyone will reincarnate much later than 1x and rank 15? I'm guessing that a bulk of people will either never reincarnate, or keep reincarnating as soon as they can until they either quit or hit 6x. So basically I think this creates a large delay in getting legends, but then makes all the legends far more powerful.
It sounds to me like this will concentrate the bonus's on lower lvl's and front load the power curve at the cost of low lvl grinding - i.e. making people stronger BEFORE they get to very high ranks becaue they killed que-teh ALOT.
I like the general idea of reincarnation, and if the choice was take it as listed or ignore it, I would take it because i think it's a large power increase (and i like power!!) But can I ask what the intent is with the change? What was the problem you are trying to solve? I hesitate to suggest changes to the idea until I know what you are trying to do. W'out knowing that the ideas will be all over the place.
Hopefully the observations are helpful even w'out suggestions.