I have had an S23 with a Volvo KAD32, which I owned between September 2002 and sold it in July 2003, having enjoyed 145 hours and around 1500 n. miles in that time. The boat was not bad at all. She cruises at 23 knots and top speed of 26 knots, maybe a knot more on each figure with a really clean bottom. At 30 pence a litre she holds about £45.00 of diesel. Range of about 100 n. miles. Few points though:
1. Realistically you need trim tabs as the boat is very tippy, especially when more then 2 or 3 people are on board, moving around - but that is a general characteristic of all Sealines recent hull designs, especially on their sterndrive boats
2. Bathing platform extends out however if used frequently will end up cracking. Fixed bathing platform very small so access by disabled / elderly / young / nervous crew difficult
3. Which dealer are you getting it from and how close are they to your intended mooring? You need to consider warrently work as I had many snags and small things that needed doing (not uncomman on any new boat)
4. Access to the bows can be tricky. Sealine have offset the cockpit on one side so the side deck to port is wider that that to starboard. However in any conditions above a Force 2/3, getting to the bow to rig fenders etc. is very difficult, especially with the full canvas canopy up
Other than these considerations which you can work around, the S23 represents good value and is good fun to drive and live with. Try to haggle dealers down to at least 5% off, possibly even 10% off. GOOD LUCK.