Perennial Sweetpea

I’ll be sowing my annual sweet peas in a couple of weeks, but am considering perennial as well, this year. Very few clematis do well for me so the perennial sweet pea might work. I’m not bothered about scent - I want a reliable & colourful climber. So, I’d like to know the disadvantages, please. Are they invasive thugs, impossible to train, unpredictable? Thanks in advance.