redflex versus adacel

It is interesting to note that RDF's dec half result was roughly the same as Adacel's (ADA):

ADA Dec NPAT $3.26mill
RDF Dec NPAT $3.33mill

It is also interesting to note that these these two great companies are increasing earnings at roughly the same rate:

ADA earnings growth: 121%
RDF earnings growth: 145%

Both companies have excellent outlooks.

However, ADA is currently trading on a historical PE of just 10.5 (forward PE of just 7), whereas RDF is trading on a historical PE of 36 (or forward PE of around 30).

Thus ADA has a market cap of only $55mill, whereas RDF has a market cap of around $300mill.

Which stock is the better buy?

RDF has higher EBIT than Adacel and larger cash reserves, so perhaps deserves a somewhat higher market cap (keeping in mind the RDF needs much more cash for operating activities than ADA). But ADA's margins are better than RDF's, so one could also argue that they derserve similar market caps.

It seems to me that RDF is fully valued (but not over valued) at its current earnings multiple, whereas ADA is massively undervalued.