Tubular A Arm over Standard? any reason why not

So i'm due for new balljoints, so i'm going to get A arms, as well as other suspention stuff this summer

Is there any reason not to get tubular A arms, as long as they can be connected to the stock K member, like the ones from PA racing

I was looking at the 03 cobra's, but after reading pauls post on k members, I checked out PA racing. They offer tubular A arms that fit on the stock K member, and they're greasable

sound good? or any other suggestions than the PA racing ones?
 
it doesn't say. Here's the one from PA Racing

It does have an available option for a 'spring perch' but i don't know what that is

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EDIT: i think i just figured out that i'm being stupid. the spring mounts directly on the a arm, so there's no point in getting a tubular a arm if you've got springs and not coilovers...