In the 15 years i have been supporting GP, I have never had an issue that I couldn't resolve. If I didn't know the answer offhand, one of the GP MVP's had already run across the issue and had graciously published their findings on the Net. Rarely did a client need to set up a Microsoft support incident.
Dynamics GP has been developed and refined for over 24 years - the software bugs have been worked out. Yes, with each new version, new functionality can present new bugs, but these get caught and solved quickly with (automatically applied) software patches.
Occasionally, there will be a question best put to the experts at Microsoft, such as: "How to handle Unit Accounts in MR, when you don't want to roll the balance forward to the next year"; or "How to redistribute Asset depreciation after a fiscal year was closed, but the when the Original Values of some large Assets needed correction (in the prior year)." The Microsoft GP support team in Fargo are really knowledgeable about the Dynamics GP software and the accounting requirements.
Microsoft monitors the Dynamics GP forums, CustomerSource and PartnerSource. These are active forums. Microsoft Support Techs or GP MVP's will always get you an answer quickly.
GP has a huge, lively, support community (GPUG). 47,000 businesses use Dynamics GP. Every day I get email feeds of the questions and answers from GPUG and Power BI User Groups.
Microsoft has re-coded all the Dynamics GP functionality from Dexterity (the original language) to HTML5, so the software is a native Web App.
With PowerGP Online, you don't need to pay for installation of Microsoft version upgrades or patches as new functions or improvements get added to GP. These are done for you by Njevity-To-Go and Microsoft.
You will be billed monthly for hosting Dynamics GP.