I love Merle to death but as a begining rider he is too much for me...
Thank goodness for your friends being there (and knowing you better than you know yourself, LOL).
I actually did break a rib out riding alone, and it was no fun at all getting back up on that horse and riding home -- well, the horse did all the work, I just held on and waited for her to get us there. VERY STUPID, but you know how it is when you're young -- you think nothing can hurt you.
It sounds like you still have Merle, then?
I really like the sound of mules, from your description -- very smart and cautious -- although having to always watch you're not being outsmarted would be tiring.
This halflinger mare isn't mine, but she's a lot like that -- testing constantly. She'll listen if you make her listen, but she tests you every single time, and it's not just a one-time thing -- she pushes until you get to the point of having to reprimand her more than I'm used to (or comfortable with). I've never used a crop before, but I haven't met anyone yet who can ride her without one -- they usually use those dull spurs on her, too, although I don't feel my leg control is good enough yet that I would consider wearing them.
I'm glad you found a horse you like -- hopefully it's a more comfortable partnership!