Well Tempered/CROFT/Harbeth...London SG or NAGAOKA

Nagaoka is one of the biggest cartridge manufacturer, the WT cart is Nagaoka OEM work. Retail is $800, not sure what is special about it, but if the cantilever is not boron and the stylus is not line contact type then it's a rip off. 

For the same money you can find state of the art MM cartridge like Audio-Technica AT-ML170 or some nice Grace (depends on the model). You will find many info about those carts in the recommended thread. Simply ignore the fact that the author of that nice MM thread prefers digital and lomc now (who cares?). 

In my opinion AT-ML170 and for example Grace Level II BR/MR are the best MM ever made. What is important for your arm is the compliance of the cartridge. AT is mid compliance, Grace is high compliance. 

Your Denon is very low compliance, but make sure to convert 100hz (japan standard) compliance to 10hz compliance. 

Charisma DL-103 with Ruby Cantilever / Line Contact stylus has Dynamic Compliance: 7 um/mN and you're using it with oil damped tonearm which retalively light mass ? What is the effective mass of WTL tonearm ? 

If you already have WTL Nagaoka all you need is just to buy stylus of the higher model and mount it on it. 

Well, this is indeed a low mass, the reason why your upgraded Denon is not performing at 100% is that you need a superheavy tonearm for it, at least double mass compared to your WT arm or even higher. You have already upgraded the aluminum cantilever/spherical tip, so all you need is a mid or high mass tonearm as a compliment to extremely low compliance of your Charisma Denon. Think about it, maybe you’re missing something.

It’s good that you don’t have WT Nagaoka cartridge, maybe you have to try Garrott Brothers p77i cartridge if you want to stick to the new carts only.

But i think you’re missing alot when it comes to MM if you’re ignoring the very best Moving Magnets from the 70s/80s era. With 10g effective mass arm you can use mid or medium-high compliance cartridges. I think you can use Garrott p77i, AT-ML170, or that Glanz MFG-610LX - they are all medium compliance.

Cheaper alternative is Ortofon M20FL Super (Fine Line stylus) - this is an old favorite of many audiogoners, today it's under $300 in top condition. Also medium compliance. 

Well, in my opinion the majority of people just read the reviews and looking for widely available cartridges, dealers pushing what they got, but what if the review is not available and your dealer does not have a certain cartridge? Does it makes this "unknown" cartridge inferior to something that comes from the very big manufacturers like Nagaoka? I guess when famous MM thread was created 90% of those forgotten cartridges were unknown, but people were shocked how good they are compared to some very expensive new carts.  

Garrott Brothers reputation is second to none, people who taking care of the brand today are very good too. The price of P77i Dynamic Coil is AUD600 (equal to $460) it’s cheaper than Nagaoka, but it’s an amazing cartridge with Garrott MicroScanner II stylus. There is a higher model in Garrott line too: the Optim with Ruby Cantilever and Fritz Geiger Signature stylus. I think this is a good alternative to Nagaoka.

An old Garrott p77 (not p77i) is one of my favorites, i remember when i bought it from fellow audiogon member i was thinking about Nagaoka MP-50 and he had it too, but explained me that Garrott is much more interesting cartridge. I’ve been using mine on Reed 3P "12 tonearm and was happy about the sound compared to many top quality MM cartridges i have in my arsenal.

However, i think the AT-ML170 is a better cartridge and the higher price for AT-ML170 is reasonable compared to Garrott p77. The construction of the cantilever of the AT-ML170 has no analogs in today’s world. It’s hollow tapered Gold-Plated Boron pipe. The stylus tip mass is extremely low. The AT-ML180 is even better.

Anyway specs on paper is not always telling you how good is the cartridge, but you can check the specs for AT-ML170 for example:

Frequency Response (Hz): 5 - 40,000
Vertical Tracking Force: 1.25 +/- 0.3
Tracking Ability (microns) at center value VTF: 90
Tracking Ability (microns) at upper value VTF: 100
Channel Separation (dB at 1kHz/10kHz): 31/21
Channel Balance (dB): 0.5
Output (mV at 1kHz), 5 cm/sec): 4
Vertical Tracking Angle: 20 degree
Stylus Shape: 0.1mm MicroLine
Stylus Construction: Nude Square Shank
Cantilever: Gold-plated BORON
Wire Uses For Coil: PCOFC
Recommended Load Impedance (ohms): 47,000
Recommended Load Capacitance (pF): 100 - 200
Dynamic Compliance @ 100Hz: 10.0
(* please note that Dynamic Compliance @10Hz will be around 18-20cu)
Static Compliance: 40.0
Cartridge Weight (grams) 7.0
Replacement Stylus: ATN170ML

This article will help you to find more interesting things about top qulity MM cartridges: http://www.regonaudio.com/Stanton881AudioTechnicaATML70.html