SL1200 upgrade tonearm or replace cartridge?

The upgrade bug has started to bite again. I'm thinking of upgrading my tonearm from a stock sl1200 tone arm with cards wires to a SME arm (309, IV, or V).

My other issue is that my cartridge, a Benz Glider homc, I nearing the point where it could use a re-tip or exchange.

My budget is limited, so I can only do one of the above this year.

So my question is, which upgrade cart or arm?

Is the glider a good fit for the SME arms?

Which SME arm is the best fit for the SL1200?
Really? Someone suggested SME iv and v for a relatively cheap turntable? All the SL1200s I have heard sounded a bit rough. It just seems like a top heavy approach.
The negatives applied to a servo/quartz DD system can easily be reversed to a belt driven one...the belt is constantly expanding and contracting...but is it audible?...if a tree falls in the forest...haha....each system type has pros/cons,,,i have enjoyed both...currently have DD....
Yes really! I can't speak for all 1200s but mine are definitely not rough sounding. Mine are early MK2 units likely from the late 70s or early 80s, the construction differs from later units I have seen. They are more robust.

In the end I modded the original arm. I replaced the S arm with a carbon fibre straight tube. The results is quite good. I had some friends over a few days ago listening and they were very impressed with the result. you can check my system for some pics.

As to the comment regarding upgrading the phono stage and cartridge. I had already done this, I am using, ARC SP16, with HO Benz Glider and this has been one of the most beneficial upgrades for my system.

I am still interested in trying the SME arm but there is currently no budget for it.
Nick, I don't think your cart needs replacing it sounded GREAT the other day and tracked like a champ, I think that you just have some audio-nervosa on it. I like the job you did on the arm, the custom carbon fiber wand/headshell/direct wire are all nice but that SME arm...enough to make an audiophile buddy VERY jealous ;)
Nick, I like what you did to the OEM arm. If you don't mind me asking, where did you source the materials? Changing to a straight tube look like a nice project.