I have a Force 40 on my wee tub. It came with the outfit, only 30 odd hours from new, not a mark on it. It ain't broke, it gives reasonable performance and economy, only minor problems (T/T relays giving up due to vibration, I think), so I shall continue to use it.
However - I would not buy another - its very old tech - runs dirty and noisy - has no peehole to indicate cooling water throughput - and spares are very hard to source - Props are not thru-hub on the pre-merc models.
Performance is also down compared to a Merc, Yam, Suzi etc - HP was measured differently - so output at prop is probably more like a 30-35HP.
As I said, I do not have any big probs with it, but I could not recommend buying one. When it comes time to replace it, I think I will invest in more modern technology.
"Remember the Plug!"