I did my CPL and Instructor training at WLAC in 1991 and they were then and, as far as I know, now a highly successful and viable organisation. However one only has to look at the number of "high street" brands that have gone into administration to realise that previous results do not guarantee future performance.
The flying training industry is littered with companies that have failed dramatically having been previously successful. I would urge anyone who is undergoing flying training (no matter through which organisation) to only "pay as you go".
If you have the money to pay up-front then put it in a bank account that provides instant access and the best rate of interest and "draw down" from that account to meet your flying costs. The interest will closely match the discount which you are offered and your money will be safe.
I would add that when I was the CFI of a flying school I used to give the same advice to any prospective customers who wished to pay "up-front".