I decided to make small reorganization in my Spectrum+. Removing the heatsink for the linear voltage regulator seemed to be a good idea, and this generally means that the linear vreg will also have to be removed (as usually it has to dissipate about 2.2W). So I had to put a replacement vreg that doesn't need a (big) heatsink. The usual rule of thumb is that small components/modules without heatsink can dissipate up to 600mW without serious concerns for their longevity. 2.2W will fry any regular electronic component, even TO-220 package, when not cooled down.
Some months ago I purchased a handfull of these switching regulators. The expected current consumption of the Speccy is about 0.5A, so it was a good match for this regulator.
Here's the old linear vreg before the change (heatsink is already removed):
And here's how it looks after the replacement with DC-DC converter:
The switching regulator has good enough efficiency (datasheet states it's up to 95%?), during normal operation of the Speccy it gets barely warm. As a result of the improved efficiency, the Speccy current consumption was reduced from 550mA to about 400mA (with 9V power supply), which is very nice.