Arm upgrade for Gyrodec SE, could use some help

Hi All,
I have a modest rig that includes:

- JA Michell Gyrodec SE (~$2400)
- Benz L0.4 MC cartridge (~$1250)
- Alphason HR-100S MCS tonearm (unknown)
- Sonic Frontiers SF-Phono1 Phono stage (~$2000)

It seems to me that the old Alphason "S" curved arm is a bit of a weak link at this point (any opinions on that assertion?), so I've been thinking about an upgrade. There are several options, and here is where I could use an opinion or two:

1) JA Michell TecnoArm - rebuilt RB-250, is it worth $1100?

2) RB-300 - probably the most common arm on Gyrodecs, and at $500 seems to be a reasonable price point. Better than the Alphason?

3) RB-700 - don't know much about it, but in the price range of the TecnoArm.

4) JWM-9T - Not sure it will fit, but beautiful arm that is well regarded ($2100)

5) SME 309 - Similar price point to the JWM, but again, will this work well in my system?

so that is my situation, I'd appreciate any opinions and recommendations you have!

Thanks,

brent

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Rest of system:

DK MkII Integrated
SFCD-1 CD player
Silverline Sonata III speakers (Thanks Grant!)
AU-24 / Harmonic Tech / Cardas