How do you go about a DIY implementation? Is it always cheaper to go direct to NS PS or can it be more competitive to engage with a SI partner? In a sticky situation as our current instance delivered by NS PS is an abomination and we need a new instance.

My experience with NS PS (for development) when I was working with a client is they are less responsive. The quality of the work was also questionable in some scripts.

Ditto. We've had it so bad that we want to descope entirely and use in-house resource. Just need a barebones instance of NS for us to work off

ugh, NS PS is the worst. There is no way to get a barebones instance without signing up again. I had a client that I took over from PS and I literally undid everything first. Deleted accounts, items, forms, transactions, etc. We really had to unwind to get rid of some of the nonsense they added.

My experience has been generally poor with NS PS, although I've heard a few people say they've gotten better in the last few years, for whatever that's worth. My rule of thumb is to only trust any implementation partner as far as I can throw them. You 100% need a dedicated internal resource that's going to hold everyone's feet to the fire (both internally and externally) and keep things on track, even if your partner is providing project management resources. You'll probably have more flexibility on pricing, scope, and support with a partner than NS PS, but you still have to do your homework and sorting through all the options to find one that's quality can be difficult/time-consuming.

I also had bad experience with NS PS too. While back we engaged them to segregate an existing company in to two separate entity with multiple subsidiaries. Process was complex and they said they can do it. Half way through their work quality became shitty, also resources were constantly being changed. They weren't even able to do simple data migration properly. So long story short we had to fire them (it was a fixed bid project) and one my colleague and I took over and finished it in time - though 16-18 hrs a day for 3 months. At my new company they started implementation (suite success) about a month before I started, once I joined I took over the most of the heavy lifting and completed the implementation way before stated deadline. For sure NS made good profit for the this implementation, because they used up less hours then the allocated ones.