@MARK1992 Bigger concern I'd have is that you will have non-matching second stages and you may not enjoy being on the R195 for half the dive compared to the S600. If you're going to get another first stage, I'd bite the bullet and get a higher performing second stage with it.
Now, if you stay with Scubapro, just understand that you will essentially be relying on a shop to service them as getting parts is a bit of a PITA since Scubapro as vehemently opposed to self service *like will cancel someones dealership status if caught opposed to it*, so it is not a brand I recommend to people who are committed to technical diving. It has nothing to do with how good they are, suitability, etc. as many of us use them, but as a technical diver, you need to be able to either self-service or afford a full backup set of regulators. Most things that go wrong with regs can be fixed in less than half an hour with minimal quantities of tools. All of this "service anywhere in the world" that gets spewed is fantastic, but are you going to pay out the nose for overnight service on a regulator? The cost of doing that is nearly the cost of the regulator itself, and you are still likely going to miss the next day of diving. If you can service yourself, then it takes an hour with some allen keys and an o-ring pick and you're not going to miss any diving. Only alternate to that is to carry spares and that ain't cheap....
about to go on a quite lengthy cave dive, non-swivel first stages. Their Poseidon 3960's, but same concept as the MK17. Biggest annoyance on the left tank is that the hoses aren't "pretty" when stowed on land, no issues in the water. Biggest annoyance on the right tank is that when you donate the long hose, it has the potential to kink off if the guy pulls too hard.
I do second
@Asheron though. A MK17 is going to run you $350, and with the S600 about $650. A full Deep6 Signature set is $900 with much lower total cost of ownership. The cost delta will get real small considering you're going to have to buy new inflator hoses- $50, another SPG w/ hose-$80, another short hose for the left bottle and potentially another for the right bottle-$20-$50, etc. So $550 if you use the R195, $850 if you get a new second stage, vs $900 and you get lower cost of ownership with the Deep6 *remember that the first service, including parts, is free so that's at least $200 with 4 stages from Scubapro if you don't have parts for life, half that if you do*.