I was in the same situation as you, having started out with Scubapros (MK17s and MK25s with G260s), and faced the same conundrum when I had to purchase more regs for technical dives.
I've considered almost every reg under the sun (mainstream ones such as SP, Apeks, Poseidon, Halcyon, XDeep, Tecline, Atomic, Mares, Zeagle, ScubaForce, HOG, Deep6 etc to the less known Chinese/Taiwan brands like Akuana, Kamaqua, IST, Aquatec), and long story short, I decided not to go on with Scubapros (or any other brand for that matter0, and instead go with the Deep 6 signature line.
My reasons are, amongst others:
(a) Scubapro regs are expensive (a substantive part of which is for marketing like all other big name brands), and I could literally get 2 Deep6 regs for the price of one SP reg. As I will definitely be buying more regs for stage and deco tanks in the future (if I were to continue down the tech route), I've decided to slowly phase out Scubapro regs for my tech diving and use them for rec diving only while I accumulate Deep6 regs for tech purposes.
(b) Deep6 is generally more supportive of owners servicing their own regs (they have the service manual online, there are courses available, service kits can be sold to non-dealers, and they are responsive to inquiries), and that aligns more with my preference to service my own regs. Caveat is that I have access to Deep6 service kits at my location, but even if you dont have, that can probably be mitigated by requesting for extra service kits when purchasing. In the meantime, there is also a first free service policy so you have up to 4 years to slowly purchase the necessary tools and learn how to service your regs. The same cannot be said for SP as they adopt a dealer-centric approach, and generally do not train and/or share their resources with their dealers.
(c) Deep6 regs are sealed diaphragms (more suited for harsh environments), and are by all accounts (both in my diving circle and on Scubaboard), fantastic regs on par with (if not better than) other name brands, with no known inherent issues. MK25s are great, but they are an unsealed piston design which might cause icing issues, or result in stuff/debris etc being trapped inside the chamber and causing longevity issues. MK17s are sealed, but they do not have a turret. MK19s are sealed and have a swivel turret, but they are much more expensive (in my region) and do not have that long of a track record (they were discontinued for quite a long time previously, and reviews on the current MK19 are scarce).
(d) Customer service and aftersales support of Deep6 are also great, where (as I've heard) they will go above and beyond to ensure customer satisfaction. With SP I believe its hit or miss with their dealers.
(d) the founder of Deep6 is the same person who started the HOG brand. They have had a good track record from a long time ago, and their business model seems to be quite viable. It would be therefore be unlikely that the brand will be discontinued, leaving me with no spare parts/service kits. SP of course also performs great in this aspect, as availability of parts is basically a non-issue.
(e) I like the business model, innovations, and options that Deep6 is bringing to the dive industry, and would like to support such a company.
Just my 2 cents, hope it is of help to you.