I have the wilcom truesizer - haven't had to use it as discovered I can reduce or increase a design by 20% right on my machine (I have the Janome MC11000SE).
Cuties will have an answer for you though.
I use SewWhatPro from SandsComputing. Free trial too. They also have great support team through the website AND yahoo groups; answers usually within the hour.
I do not know how I ever did without basic Embird and its Iconizer plug-in. So many great features for the cost! You can only increase/decrease a design by approx. 20%. If you go more you lose or add too many stitches resulting in a poor stitchout of the original design. You can always add Studio, the digitizing plug-in later, should you want to create your own designs.
Angel
I'm not offering a solution here, but just a bit of information: Whatever software you are looking for, be aware that you might ask for the impossible! There are cases which simply can not be scaled without loosing quality. You can of course always scale stitch positions directly - changing the stitch density, as you know - but scaling AND keeping the stitch density is a kind of "re-digitizing" of a design, and there are limits for that. a) The source file might not have the proper information for it (e.g. it has the stitches saved, but not the "lines" behind it) b) Even if lines/areas etc. can be scaled, "re-interpreting" them into embroidery can cause a lot of troubles and mistakes. In short: If you scale a lot, don't expect perfect results!
Embird. I don't think I would embroidery without it. Honestly.
I have Brother 6500, use Embird, and so far it works very well.
Brothers own PE Design program is the best. Go to your local Brother agent and ask them about it.
I use free Wilcom Trusizer, you should never change a design by more than 20% and then test it to see if it has become distorted. I also have a Brother machine, low end SE-350.