Have had my Level 6 mitts for almost two years. Actual usage is way less than a season since I only use them for the "transitional" period from cool to cold (i.e. several weeks late fall and late spring) since they are only 2 mm neo.
Surfing this weekend, felt my hands getting chilled after about a hour of surfing. That's pretty quick given that the water temps are still in the low 40's. Not that cold at all. Anyway, checked the mitts this morning and found three small splits in seams of the left hand - on along the thumb, another along the index finger and another on the seam at the bottom of the hand. There was another split seam along the thumb area of the right hand. In contrast, my NRS Toaster Mitts lasted more than two winter seasons before a split developed on the seam between the thumb and index finger of the left hand. (More pressure on the seams of the left hand mitt since I tend to roll more on that side.)
I think the increased number of split seams with the Level 6 is due to glue-only seams and the lack of a preform grip shape. The L6 mitts constantly twist(on the waxed paddle loom) from sprinting out through the break zone and rolling in the breakers. The glue only seams evidently can't withstand too much of this.
In contrast, the pre-formed grip shape of the NRS Toaster Mitts (3.5 mm with 2.5 mm palm) minimizes the twisting I feel/see with the Level 6 mitts. And the glued AND blind stitched seams of the NRS mitts evidently hold up better. I'd glued and restitched the split NRS seam and it's held up through the past winter. I'll be using these for the rest of my winter surf season.
If you put your winter mitts through serious heavy duty use, I say go higher with NRS Toaster Mitts. It's maybe $5-10 more but well worth the warmth (AND safety) factor for winter rough water use.
sing
but…but…but…
…the L6 has the built in nose wipe!!! 
And mine aren’t showing any wear yet, although it might be due to the fact I haven’t used them yet in the year i have owned them!! LOL
I would have guessed…
…In fact, I did guess this would be the case when comparing the two at the paddle shop where I bought my Toaster Mitts.
What did you use for glue in that repair, Sing? Aqua Seal?
Level 6 Gloves
I hear you. My Level 6 gloves lasted me only one winter season-wore through the seam at the thumb cradle as well. Poor consumer that I am (faced withe realization that; “Hey, it’s cold now and I want to go paddling!”), I just purchased another pair, as I found them warmer than a comparable NRS version. I may try to contact them to see if they’ll honor them. Warm glove-questionable QC/longevity of materials.
I’ve put five seasons on two pairs
of Level 6 Mitts. Of course I’m using them for canoeing, and I do wax my shaft, but there isn’t nearly as much sliding as with a greenland stick. However, I don’t experience any of the twisting that you describe. While I have had a seam fail on one pair, it was due to their snugger fit. The mitt would create a vacuum and when I pulled it off, I was putting too much pressure on the seam. I speedy-stitched it the tear and used Aqua-seal and haven’t had additional issues. I still love them and recommend them over the Toaster Mitts as the Level 6 Mitt waterproofness trumps wet-and-warm hands in my book.
How can you belittle Level 6 when you state that your Toaster Mitts blew a seam too?
I have five pair of NRS gloves. All of them have had their seams blowout on me. NRS uses under-spec thread in my opinion as nothing has torn, the thread just broke.
For those that use gear, the Mantra should be, find what works, then reinforce.
age
Wait till you get a little older and holding your hands in one position for long periods of time causes cramps. That’s the big downside to the toaster mits.
Bill H.
storage
Btw, off season storage is often an issue with most paddling clothing life. This stuff hates UV and flourescent lights produce lots of it, along with the sun. Have to use care in how this gear is stored when it’s not being used.
Bill H.
Neoprene Glue…
got it from a dive shop. The stuff doesn’t seem to dry up and become useless after the can is opened, like Aquaseal seems to do once the tube has been opened. Aquaseal will work too.
I stitch up the split with spacing that allows me to work in glue in afterwards. Then I brush on more neoprene over the thread holes, inside and out.
sing
Goes Both Ways Then…
trying to maintain a grip with resistant neo would then cause cramps as well.
Old… age is factor. Staying in shape is a better factor.
sing
Not an adolescent either.