<< There are a few other positive considerations:
 1: Weight.  Typically turbines are much lighter than recip engines for the
 same or greater horsepower.
 2: Reliability:  Turbine engines are much more reliable. (Certified anyway)
 than recip engines. >>

One can easily say that these are the two biggest misconceptions about
turbine engines as well.

1. Weight.  Sea level, static HP or thrust (for turboshaft and turbofan
engines respectively) is not cruise HP or thrust at M .40 at FL250.  Turbine
engines are normally aspirated, single cycle engines.  An Otto/Brayton
combined cycle will always beat an Otto or Brayton cycle on their own.  At
FL180, your combined cycle TSIO-550N is catching up fast to a comparable
weight class turbine in terms of thrust to installed weight.  

Therein lies the second caveat on the weight issue:  installed weight vs.
book weight.  Continental and Lycoming lie like politicians about their book
weight, but can't hold a candle to most turbine manufacturers.  I don't have
personal experience with the engine in question, but the difference between
the book and installed weight of a PT6-67A is almost 40%!  Wait for a side by
side aircraft comparison before believing that "100 lb." advantage...

As you speed up in a turbine, two things happen:  the SFC rises
disproportionately vs. the thrust rise from ram effect;  and the total
equivalent HP drops off due to the loss of residual exhaust thrust with
speed.  That turbine exhaust is coming out only so fast.  At seal level, it's
quite a boost.  At speed, it's not so much.

2. Reliability.  Almost no one gets full TBO from a high performance engine,
right?  Wrong.  The better charter operators have been doing it for years as
have many flight schools (show me worse operating conditions).  At the same
time, the owner flown Mirage that makes TBO without a jug change has yet to
be found.  Most B55 operators make TBO without a jug off, while few B36TC can
keep their engines out of the shop.  We can only say from this that piston
engine reliability is mixed bag of make, model, operation and maintenance.

Turbines never fail, right?  Nope, sorry.  IFSR (in flight shut down rate) of
turbines of the generation being discussed is pretty poor.  Yes, modern
turbines with either FADEC or rudimentary temperature-based fuel limiting
controls are quite reliable.  Neither the Walter, nor the ATP has these
protections.  Shove the throttle up too fast and not watch the TIT like a
hawk and WOOOOOOFFFFF!  There goes the hot section.  You're now a glider, and
the rebuild will cost you more than a new piston engine.  This is not
hypothetical, it's happened on everything from a CF-6 on a DC-10-30 to the
AI-25 on the L-39.  It'll happen to your turbine Lancair if you throttle up
too quick.

Power to weight and power to $$$, the turbine is unbeatable at sea level.  At
altitude, not below 2,000 to 5,000 HP.

Gary Casey summarizes most of the issues with small turbines well.  For me, I
worry that many are investing in heavy and expensive turbine engines thinking
they are getting a piece of modern airliner technology when they are not.  
When it flies and it flies side by side with a well tuned piston version of
the same aircraft, THEN we can make a comparison.  So far, that comparison
has shown small turbines to be less than we had hoped for.

In the meantime, I will wait for a modern (and cheaper) Jet A piston.  No,
not the expensive nonsense coming from SMA, nor the auto conversion certified
by Theilert, nor the government welfare R&D of Zoche.  Yea, the holy grail is
out there, it just hasn't made it to our market yet...

Eric