Wordbiker

While Retro nailed it on the head with that statement, here are a few things to consider:

The Trek Y3 was introduced as an entry-level MTB. Many sacrifices were made in component quality to compensate for the additional expense of the suspension frame design and shock, and still keep a low pricepoint. This practice makes for a signifigantly heavier machine with poorer components compared to a hardtail at the same price.

The suspension design of the Y3 was outdated, even by 1999 standards. Most manufacturers 'trickle-down' suspension designs, saving the cutting edge expensive designs for the top of the line and dumping the old tech into the lower lines where most consumers are more concerned with price than sheer performance. Trek is no exception to this practice, and may be even more resistant than other brands to introduce new concepts.

Until last year all Treks had a single pivot rear suspension design. While this is not inherently a bad thing, there are certain traits of single pivots that some riders do not like, such as "inchworming", chain feedback through the pedals, or activation of the suspension under braking or pedaling. To fix this, Trek (and other single pivot manufacturers) adopted a platform shock design to lock out the bad traits, in essence turning the bike into a hardtail when the lockout lever is flipped, while still retaining the extra weight in the frame and shock. While the platform system does work well, just keep in mind that it is masking undesirable traits, not removing them completely. Trek's move (finally) to a multiple pivot design should say something about what they feel is the superior suspension.

While Trek for the most part has kept their designs simple (and has used that simplicity as a marketing tool), other manufacturers have developed a large number of proven designs that have had great acceptance for their performance traits. Four-bar linkages, Horst link/MacPherson strut, and Virtual Pivot Point designs among other variations were all aimed at having the full travel the bike is capable of at all times, climbing or descending, braking or accellerating, with as little change to handling properties as possible. If these designs had failed in that task completely, they would not be seen dominating the market today.

As you may have appreciated, simplicity can still be a good thing. Your hardtail 3700 offers a great deal of value for the money, especially when compared to a suspended bike at a similar price point. Much lighter, better components and less tuning and maintenance required make the hardtail a solid choice for any beginner, and many pros would still choose a hardtail for racing if their contracts did not require them to ride full suspension.

Selling Trek, Giant, Specialized and several other brands, I have had to deprogram myself regarding my own brand loyalty. Our job is to fit you to a bike that suits your intended usage and budget, regardless of what decals are on the frame. Whether a brand fits into an image you wish to project, or once having ridden a brand you like makes you more comfortable continuing to choose that brand is up to the individual. The only pitfall of brand loyalty is to not consider the traits other brands or types that may very well suit you better. I can tell you from experience that choosing the wrong bike from the "right" manufacturer will eventually lead to dissatisfaction...unless you never ride anything else and don't train yourself to notice the differences.