Simon,
I've used a RoHo commercial a few times as you can hire them from RoHo. I found them alright, had no problems. Lots of people in our club use them as a "starter" suit, and then move towards the RoHo Technical as I think it's better material.
If you can wait they'll be selling all this years hire kit off at the end of the year. I think it's usually about 50% discount on shop prices.
You could also look at this special offer suit
http://www.roho.co.uk/dive/diving_offers.html. It's the same material as the Commercial. Apparetnly It's cheaper cos they are only doing limited off the peg sizes and it just comes in one colour (black/grey).
I own an Otter Skin which I think is excellent. You'll find lots of recommendations for them on here. Divers Warehouse are having a massive relocation sale at the moment. They have loads of ex-hire and existing stock dry suits on sale (Otter Skins and Neoprenes). I was there on Saturday and there seemed to be some great bargains. The sale is on for two weeks.
Hope this helps.