It's a difficult one to answer because Hubspot is a continuously evolving platform. What isn't working so well today will be great tomorrow. The speed at which they are developing is mind blowing. I've been watching this now for 1.5 years and it's pretty amazing.
They're doing some pretty cool stuff and constantly pushing the boundaries, I wouldn't want to single any one thing out, none that might not be 100% of the parts will remain so. I just don't know in which order they develop but I know they have a team behind every aspect and like I said keep evolving the product.
So if the question comes of whether it'll be a problem because perhaps there is something that another software might be better in, it won't be long before that's no longer true. Buying into Hubspot means buying into constant change and evolution - that by itself could be a bit of an issue for some people but in my books that's their greatest plus, despite the constant learning curve.

The right mentor is the one that you have respect for and who irritates you just enough to push you towards your next goal :)

It sounds like you want some advice on whether your idea is a viable one. To me success happens at the convergence of your passion, your knowledge, and the market. If those 3 play in your favour you're set to go.
If they're not you got some homework to do.

I am a small business and marketing coach and can ask you the right questions to find your answers. If you're looking for more technical how to questions I'm not the ideal person. I have some technical background but it's not my full expertise. So it really depends what you need right now.

Want to figure out if you should do it and what the next step would be if so? That's the one I can help you with.