I asked this at Rutland Water last year.
Was told they are for ‘very’ occasional users. If you want to use it more than twice a year, get a solid one. Others have pointed out the pitfalls above.
The only upside I can think of is the ease of storage and transport.
What are you thinking of doing?
I took a 2 hour lesson after not doing it for 20 years, and loved it, even on the flat calm Rutland Water. Unfortunately business for me took a large downturn last year, so I never got round to buying one, but I had intended to start on local rivers/canals, then try some of the Peak District rivers with a Club.
Alan.