Apprehensive to go multisite with wpmu

I'll be truly honest with you guys, I have been apprehensive to go on year long plan with you guys, I have a small business with plans of growing, for me so far has been ok, I have little clients with simple sites that have individual hosts and domains paid by them, and I develop and update, so I was thinking of going multisite, with godaddy (since it's my current host for years) I had a cpanel plan but even after setting up wildcards and dedicated ip, I can't seem to be able to make domain mapping to work and it was slow as molasses, i have gone back to my current plan of doing individual sites, but that whole login/logout, login again feels counter productive, so... in order for me to consider going on an annual plan with all the nice things you have, which things I should do to make this work?, and should I invest in a vps instead?, since it would have more resources available in terms of speeding up the whole multisite platform. I think for a multisite installation 1 GB of memory should be enough, what do you think? thank you for your time, keep up the good work!