Speaking to some of our installers (MAP Electrical), the wages can be bad, but if you get good then you can earn a reasonable amount, most of them round our way start at 7:30 ish and generally get done by 4pm though there's usually extra jobs that can be picked up from the lazier bodies.
A shortage of work isn't very likely especially as the sales teams are being increased in size.
As long as you do the job properly and don't cause any grief, try to bend rules etc. you generally get your work first thing in the morning and are then left to get on with it.
No two days are the same, and your always meeting new people.
Downsides,
The supervisors and managers can be unpleasant at times (in fact if I was being spoken to the way that I overheard the other day I'd have twatted the bugger and told him were to stick his job) as they tend to treat all the workforce the same and some of the lads need an awful lot of jumping on

Hard work to make a decent wage.
Out in all weathers.
Limited scope for sick & holiday pay.
Pay for your own tools but this is not really any different to most tradesmen, and isn't normally taken in one go but over a period of months.
TBH if your already on piece work then that side of it shouldn't bother you so the only real choice is going to be can you put up with the other downsides.
I thoroughly enjoyed my time as an installer, though admittedly it was a long time ago and in-house for one of the smaller companies that were snaffled up.