Pianotech

I don't think Ronsen hammers are appropriate for that piano, although I did put a set of Wurzen hammers on one for someone who really wanted the sound they produced. It lacked power in my view and produced tone that was a little too dark for me for that piano but the customer wanted that. I would stick with Renner products for that one and use either blues or blue points. The wear on those hammers has also been faster than I would like to see which might be related to softer hammers on high tension scales, not sure-he does play a lot. They do sell the Bosendorfer hammer but be prepared if you use that as they require extensive needling in the initial phase.  

That piano generally wants a bit more mass and firmness in the hammer and there's a problem when you use a relatively soft hammer there as it forces you into an16 lb hammer which means a lot of bulk. That added mass tends to darken the tone and you will have to harden them which I don't care for on that piano.. Softer hammers generally benefit from being low mass (Steinway hammers from the 90s or early 2000s are good examples of soft hammers with too much mass).  So, depending on what the action will handle in terms of weight I would opt for a Gr4 or even a Gr5 hammer from Renner. I would probably lean toward blue points.