Cool man. Thanks for the PM.
I'll get you a box out here in the next few days. I'd love to hear what you like and what you don't.
Amongst others, I'll be sending you two pairs of SHOWA NSK24s and some Ansell acrylic-lined nitrile gloves that are very similar to the SHOWA 720s... Just a different brand and color and fit - which might be perfect for you. There will also be some neoprene gloves in there (flat neo, not wetsuit foam neo) that you also might like.
When you receive them, you're going to obviously be looking for fit, stretch, and thinness (tactile feel and dexterity) - probably in that order - but if those are the only qualifications that we divers were looking for, we'd all be in thin latex gloves. The other qualifications that we're looking for is resistance to mechanical hazards like abrasions, cuts, tears and punctures... And latex rates very poorly in those categories. Latex also transmits heat and cold extremely efficiently, which means to a diver that the glove is very cold... So with latex, an underglove is a necessity - which can nullify the whole point of fit, stretch, tactile feel, and dexterity, depending on what underglove is worn with the latex glove.
For some divers, it doesn't really matter - their diving consists mostly of non-hazardous conditions like a clear lake with no barnacles or oysters, and sanitized "wrecks" with no sharp edges. But for most of us, diving is typically done in environments with rocks and barnacles and oysters and torn metal. For those of us who depend on the glove for suit watertightness (eg. wrist seals don't seal), being able to keep the integrity of the glove is paramount.
Given that you've chosen to dive with SHOWA 660s and 620s, I gather that you're a member of the latter pact, not the former.
...Anyway, every glove made by the major glove manufacturers have ratings that demonstrate the glove's ability to resist mechanical hazards like abrasions, cuts, tears, and punctures. My personal favorite rating - and the one I most readily believe - is the EN388 rating, which is a European standard.
For a complete explanation of the EN388 rating, see this article:
EN 388:2016 | Guide
In short, each glove assessed by the EN388 rating has a four-digit number that corresponds to the glove's ability to resist certain mechanical hazards. The first digit is a grade from 1-5 on the glove's resistance to abrasion. The second is a grade 1-5 on the glove's resistance to cuts. The second is 1-5 on tearing, and the last is 1-5 on punctures.
Latex gloves don't even rate a 1 on the EN388 scale.
660s have a rating of 4121.
620s have a rating of 3121 - which means that they're slightly less abrasion resistant than the 660, which makes sense since the material is thinner - but otherwise identical in its resistance to the other hazards.
720s have a rating of 3132, which means that they're the same abrasion and cut resistance as the 620, but more tear and puncture resistant than either the 620 or the 660. Given that it's also stretchier and thinner, this is a win on all fronts... Not to mention that nitrile has natural insulative properties to it that keep a diver warmer, making him/her rely on undergloves less - which aids in dexterity and tactile feel of the glove. This is why I'm a big fan of the 720... Warmer, thinner, stretchier, and tougher - all at the same time - over a PVC glove like the 620 or 660.
Anyway - the NSK24, which is also nitrile, has a rating of 4111, which means that they're as abrasion, cut, and puncture resistant as the 660s, and slightly less tear resistant... But are thinner and stretchier and warmer while offering the same fit. They're also textured - which gives a pretty amazing grip. I suspect that you'll like them.
...So yeah - there ya go. Take a look at what I send you and choose what gloves to try based on your initial impressions... Then look the glove up on the manufacturer's website and check out the EN388 ratings to compare it's toughness against mechanical hazards. Then dive them to see what's warm and what's not.