Wolverhampton / Halfpenny Green has transformed out of all recognition recently. Back in the "Wolverhampton Spaceport" days they were inflexible, expensive, and generally unfriendly.
I'm not quite sure when the change happened, but I've heard nothing but good of the place recently - and several recent visits I've made they couldn't do enough for us.
Piperboy - the 2-strokes are cheaper to buy, have a better power-to-weight, and for a sole-owned aeroplane that fly low hours, probably only need a significant service every 5 years. So for older, and privately owned aeroplanes, they make a lot of sense. The 4-strokes are heavier, more expensive, but for a high-useage aeroplane the longer service intervals and lower fuel burn are really worth having. So, the 2-stroke aeroplanes tend to be either the older (pre-1999 when the microlight weight limit changed from 390kg to 450kg) aeroplanes, or the sole-owned aeroplanes. Not a universal rule, but a common one.
In reality however, all microlights have had to meet strict noise limits for years, whilst light aeroplanes have yet to have such limits applied in the UK. So it's really not clearcut.
G