Pantone+ CMYK conversion differences

Hi Everyone

Im noticing some strange differences with CMYK values when converting from Pantone+ Solid uncoated.

in Indesign Pantone+ 342U when converting to CMYK gives me a breakdown of C:76, M:40, Y:58, K:18.

But we also have enfocus pitstop, with which we do quite alot of editing, with pitstop there are two sets of pantone+ colour libraries; version 3 and a seemingly newer version 4 (Pantone+ Solid uncoated-v3 & Pantone+ Solid uncoated-v4). These two different libraries give me different conversions compared to indesign, and are also different between the two of them.

In Pitstop with Pantone+ Solid uncoated-v3, Pantone+ 342U when using their CMYK Colour space, gives me a CMYK Breakdown of C:96, M:7, Y:80, K:33. When using pitstop's lab colour space the breakdown is L: 43.06, A: -19.82, B: 2.61, which when I convert that to CMYK in Indesign gives me a the same CMYK Breakdown as it does when using the libraries from within Indesign... C:76, M:40, Y:58, K:18.

But when using Pitstop with Pantone+ Solid uncoated-v4, I get different results again. In this instance when using their CMYK Colour space, gives me a CMYK Breakdown of C:92, M:12, Y:66, K:43.

If I use pitstops lab colour space with Pantone+ Solid uncoated-v4, it gives me the same values as in Pantone+ Solid uncoated-v3. Which is L: 43.06, A: -19.82, B: 2.61, which again gives me a CMYK conversion of C:76, M:40, Y:58, K:18, which as i said earlier is the same as the breakdown Indesign gives me.

My concern is which conversion is correct? Obviously we need colour consistency accross jobs and we use both applications intensively, placing supplied pdfs with various embedded pantones. Is it safe to use the pantones that carry through from the pdf through pitstop (after editing) into our Indesign swatch libraries? Or am we supposed to Alias these pitstop swatches with the equivilant swatch from within Indesign? Which ones are correct? 

Looking at the pantone swatch books we have the situation becomes more muddled with the conversions numbers being different again. And with Pantone now seperating from Adobe, im wondering whether it will continue to change?

So any ideas which conversion data is correct?