Victor UA-7082 Arm OR Micro Seiki MA505L ...? (both fit my existing alternate 270mm hole)

Personal Experiences:

Part of a smashed kit I bought and returned: It had a UA-7045 with a bad grommet, took it apart, measured, found rubber stepped washer fix at home depot, but returned the smashed kit, never installed/used it. I would use my AT headshell with adjustable azimuth if needed, the MA505L armtube fitting is itself adjustable for azimuth

I installed a pair of MA505's long and short for a friend, took them apart, set them up, played them, I like everything about them. 

A caution for anyone considering the MS 505.  I've mentioned this elsewhere but repeat it here.

I agree with Elliot that it is a very good arm.  However many used examples have damage to the stub where the counterweight is mounted.  This is easy to determine, make sure the stub is in the same plane as the arm tube.  Many of them sag or are slightly drooped.

There is a cushion where the stub is mounted which can deteriorate with time.  That should not be overly difficult to replace unless the mounting screw is stripped.  Mine was and I had to send it to a specialist for repair.

Some may claim the stub droop is original design but it is not.

Pryso, are you sure you are not thinking of the Victor tonearm, not the MS? The drooping counterweight on the former tonearms (7045 and 7082) has been much debated here. I would argue, and did argue that the droop is actually a potential upgrade to the original, albeit unintended, if the weight is hanging at only a shallow angle, because a perfect shallow droop would place the center of mass of the CW closer to the plane of the LP surface, which is a deliberate and desireable feature of many more modern designs. I don’t argue that the droop is part of the original design, just that it may be accidentally serendipitous. I own a 7045 that droops and did also own an MS505. I don’t recall that it too used a rubber grommet between the pivot and the CW but maybe so.

Many of us are aware it is the Victor 7045 and 7082 arms that have a rubber grommet, like the SME 3009 3012 arms, that isolates the rear counterweight section from behind the bearing and forward parts of the arm, and they deteriorate. SME’s concealed long tube grommet age and rot, I replaced mine with OEM part, but are harder to see, the Victor stepped grommet weakens, tears, Sag is obvious, perhaps even beneficial for a time as lewm mentions, until it further deteriorates.

My post: Victor UA-7082 Arm (good grommet)

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Aside from that, what choice would you make?

I like them both, but never installed or used the Victor Arm like I have the Micro Seiki on my friend’s Luxman PD444